Calamos Investment Trust N-CSRCertified annual shareholder report (management investment company)

TIMELY INFORMATION INSIDE

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Family of Funds

ANNUAL REPORT OCTOBER 31, 2021

Alternative

Calamos Market Neutral Income Fund

Calamos Hedged Equity Fund

Calamos Phineus Long/Short Fund

Convertible

Calamos Convertible Fund

Calamos Global Convertible Fund

US Equity

Calamos Timpani Small Cap Growth Fund

Calamos Timpani SMID Growth Fund

Calamos Growth Fund

Calamos Growth and Income Fund

Calamos Dividend Growth Fund

Calamos Select Fund

Global Equity

Calamos International Growth Fund

Calamos Evolving World Growth Fund

Calamos Global Equity Fund

Calamos Global Opportunities Fund (formerly,
Calamos Global Growth and Income Fund)

Fixed Income

Calamos Total Return Bond Fund

Calamos High Income Opportunities Fund

Calamos Short-Term Bond Fund

Experience and Foresight

About Calamos Investments

For over 40 years, we have helped investors like you manage and build wealth to meet long-term objectives. Because investors have different time horizons, risk tolerances and goals, we offer funds to suit a variety of asset allocation needs. Our 18 mutual funds include equity, fixed income, convertible and alternative funds. We offer US funds as well as global and international choices.

We are dedicated to helping our clients build and protect wealth. We understand when you entrust us with your assets, you also entrust us with your achievements, goals and aspirations. We believe we best honor this trust by making investment decisions guided by integrity, discipline and our conscientious research.

We believe an active, risk-conscious approach is essential for wealth creation. In our early years, we pioneered the use of convertible securities as a means to control risk in volatile markets. We followed with strategies that combine convertibles and stocks, with the aim of participating in equity market upside with potentially less volatility than an all-stock portfolio. In 1990, we introduced our first stock fund, which invests in growth companies both large and small. Across our funds, our investment process seeks to manage risk at multiple levels and draws upon our experience investing through many market cycles. In a rapidly changing environment, we believe that this active management is essential.

We are global in our perspective. We believe globalization offers tremendous opportunities for countries and companies all over the world. In our US, global and international portfolios, we are seeking to capitalize on the potential growth of the global economy.

We believe there are opportunities in all markets. Our history traces back to the 1970s, a period of significant volatility and economic concerns. Since then, we have invested through the ebb and flow of multiple markets, each with its own set of challenges. Out of this experience comes our belief that the flipside of volatility is opportunity.

TABLE OF CONTENTS

Letter to Shareholders

JOHN P. CALAMOS, SR.

Founder, Chairman, and Global Chief Investment Officer

Dear Fellow Shareholder:

Welcome to your annual report for the 12 months ending October 31, 2021. In this report you will find commentary from the Calamos portfolio management teams, as well as a listing of portfolio holdings, financial statements and highlights, and detailed information about the performance and positioning of the Calamos Funds.

Market Review

During the annual period, the global economy continued on its recovery trajectory, supported by Covid-19 vaccination progress, reopening activity, strong corporate earnings and consumer activity, and accommodative monetary policy. Equities and convertible securities posted robust returns, with US markets leading. In fixed-income markets, high-yield bonds also advanced at a brisk clip, outpacing investment-grade issues.*

However, markets were choppy and rotational. Market turbulence increased during the second half of the period as economic recovery showed signs of moderating to a more sustainable pace. Although economic and company fundamentals remained strong, investors grappled with a challenging newsfeed. Inflation pressures intensified, supply chain disruptions persisted, and oil and other energy-related commodity prices soared. Meanwhile, anxiety around the Covid-19 delta variant temporarily dampened optimism about vaccination efforts. Fiscal policy uncertainty deepened in the United States as politicians debated additional stimulus, taxes, regulations, the debt ceiling, and a massive infrastructure plan.

Investor apprehension about interest rates and monetary policy also increased, particularly after the Federal Reserve announced in September that it would soon taper its asset purchase program and indicated it could begin raising short-term interest rates by late 2022. In the wake of this development, the yield of the 10-year Treasury bond spiked upward and closed the period nearly double where it started.

Outlook

As our teams will discuss in greater detail in the commentaries that follow, we see many opportunities across asset classes. However, this is not a period when "a rising tide will

Letter to Shareholders

lift all boats." A unique set of crosscurrents is shaping the markets as new growth themes emerge. There will be winners and losers as the world continues through a period of accelerated disruption and complex transitions.

Individual security selection will be especially important during this phase of the economic cycle. We expect saw-toothed and rotational markets to persist given the uncertainties surrounding inflation, interest rates and the pace of economic expansion. We are closely monitoring fiscal policy and remain attuned to the far-reaching impacts that spending, regulations and taxes may have on households, small businesses, large corporations and the economy as a whole.

In this environment, we believe market conditions will favor active managers who can respond to evolving conditions quickly and with a long-term perspective. Our teams use short-term sell-offs as opportunities to purchase attractive securities, with the goal of continually improving the risk and return characteristics of the Funds.

We encourage investors to maintain a similar long-term perspective and to avoid getting caught up in a single headline or data point. It's important to remember that every cycle is different. Rising inflation and slowing growth have historically set the stage for "stagflation," but this cycle is like no other. The global economy is in the midst of an extraordinary recovery period, and a moderation of economic growth from peak levels should come as no surprise. Additionally, although inflation may not be as "transitory" as we once thought it would be, we do not believe inflation data is signaling an imminent end to the recovery.

There are many positive factors that can sustain economic expansion. Vaccination efforts continue around the world, and promising results for emerging treatments are welcome news. Although we can never rule out a policy mistake, we expect the Federal Reserve to pursue a gradual course with the goal of supporting economic growth. The most recent round of corporate earnings announcements has included many upside surprises, corporate revenues are strong, and profit margins are improving. Inflation does not appear to have eroded pricing power for many businesses, which bodes well for earnings growth. Meanwhile, US unemployment numbers continue to drop, wages are rising, and many households have healthy savings and low debt. We are seeing encouraging data from other economies outside the United States, which can help set the stage for a more synchronized global recovery.

Asset Allocation Considerations

Although it is important to maintain long-term focus and avoid making short-term moves to try to time the markets, periodic asset allocation assessments help ensure your mutual fund portfolio is aligned with evolving

Letter to Shareholders

opportunities and your personal circumstances. Given the many crosscurrents in the markets, you may find that you need to rebalance your asset allocation to best address your financial goals.

For example, during periods of economic growth and rising inflation, stocks have tended to enjoy tailwinds. Although stocks have enjoyed good gains, we see additional upside for a wide range of companies, including a diverse selection of growth-oriented investments. Valuations are attractive in many pockets of the market, particularly in smaller companies. To learn more about these opportunities, I invite you to review the commentaries for Calamos Timpani Small Cap Growth Fund, a small-cap growth offering, and Calamos Growth Fund, which invests in a wide range of growth opportunities.

There's never a "perfect" time to invest—volatility is always a part of the investing landscape. However, with a risk-managed portfolio foundation in place, it may be easier to ride out the ups and downs in the market. For this reason, Calamos offers a range of funds that seek lower-volatility participation in the stock market. These include Calamos Growth and Income Fund, Calamos Convertible Fund and Calamos Global Opportunities Fund, all of which provide access to our decades of experience using convertible securities to pursue enhanced risk/reward. Convertible securities are hybrid instruments that blend stock and fixed-income characteristics. With active management, they can provide an attractive way to pursue stock market upside with potentially less exposure to the downside. Additionally, convertible securities have historically outperformed traditional bonds when interest rates rise, which makes them an especially attractive choice in the current environment.

In saw-toothed and rotational markets, investors may wish to enhance their overall equity asset allocation with liquid alternative funds, which can employ a breadth of strategies to capitalize on evolving market conditions. For example, Calamos Phineus Long/Short Fund follows a flexible approach to seek strong risk-adjusted and absolute returns across the global equity universe. Meanwhile, Calamos Hedged Equity Fund employs sophisticated strategies to seek upside equity participation while limiting exposure to downside equity risk. You can learn more about each fund in this report.

As we've discussed in previous letters, fixed-income funds form an important strategic cornerstone for many investors. However, because rising interest rates tend to create headwinds for traditional fixed-income securities, many investors may find it prudent to make enhancements to their fixed-income allocations. Nontraditional strategies such as Calamos Market Neutral Income Fund (a fixed-income liquid alternative fund) or Calamos High Income Opportunities Fund (a high-yield bond fund) may provide compelling additions with potentially less interest rate risk than traditional bond investments.

Letter to Shareholders

Conclusion

On behalf of all of us at Calamos Investments, thank you for your trust. We are honored to serve you and help you achieve your asset allocation goals. I invite you to visit our website, www.calamos.com, for ongoing updates about the markets and thought leadership from our teams. We also provide information about asset allocation strategies for investors seeking income, capital appreciation, or both.

Sincerely,

John P. Calamos, Sr.
Founder, Chairman, and Global Chief Investment Officer

Before investing, carefully consider a fund's investment objectives, risks, charges and expenses. Please see the prospectus containing this and other information or call 800.582.6959. Please read the prospectus carefully. Performance data represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

Diversification and asset allocation do not guarantee a profit or protection against a loss. Investments in alternative strategies may not be suitable for all investors.

*  Returns for the 12 months ended October 31, 2021: The S&P 500 Index, a measure of the US stock market, returned 42.91%. The MSCI All Country World Index, a measure of global stock market performance, returned 37.86%. The MSCI Emerging Market Index, a measure of emerging market equity performance, returned 17.33%. The ICE BofA All US Convertibles Index, a measure of the US convertible securities market, returned 32.95%. The Refinitiv Global Convertible Bond Index, a measure of the global convertible bond market, returned 22.18%. The Bloomberg US High Yield 2% Issuer Capped Index, a measure of the performance of high-yield corporate bonds with a maximum allocation of 2% to any one issuer, returned 10.53%. The Bloomberg US Aggregate Bond Index, a measure of the US investment-grade bond market, returned -0.48%.

Source: Calamos Advisors LLC.

Unmanaged index returns assume reinvestment of any and all distributions and, unlike fund returns, do not reflect fees, expenses or sales charges. Investors cannot invest directly in an index. Returns are in US dollar terms.

Investments in overseas markets pose special risks, including currency fluctuation and political risks. These risks are generally intensified for investments in emerging markets. Countries, regions, and sectors mentioned are presented to illustrate countries, regions, and sectors in which a fund may invest. There are certain risks involved with investing in convertible securities in addition to market risk, such as call risk, dividend risk, liquidity risk and default risk, which should be carefully considered prior to investing.

Investments in alternative strategies may not be suitable for all investors.

Fund holdings are subject to change daily. The Funds are actively managed. The information contained herein is based on internal research derived from various sources and does not purport to be statements of all material facts relating to the securities mentioned. The information contained herein, while not guaranteed as to accuracy or completeness, has been obtained from sources we believe to be reliable.

Opinions are as of the publication date, subject to change and may not come to pass.

This information is being provided for informational purposes only and should not be considered investment advice or an offer to buy or sell any security in the portfolio.

Calamos Market Neutral Income Fund

CALAMOS MARKET NEUTRAL INCOME FUND

INVESTMENT TEAM DISCUSSION

Please discuss the Fund's strategy and role within an asset allocation.

Launched more than 30 years ago, Calamos Market Neutral Income Fund represents one of the first liquid alternative mutual funds and blends two main strategies—convertible arbitrage and hedged equity—with the aim of monetizing volatility. In addition to offering an attractive historical risk/reward profile, the Fund may enhance long-term portfolio diversification potential, especially in relation to fixed-income securities.

Recently, bouts of historically elevated equity volatility underscore the value of diversification.

Calamos Market Neutral Income Fund is designed to do the following:

ⁿ  Potentially enhance an investor's fixed-income allocation.

ⁿ  Actively pursue equity market upside while hedging downside risk.

The end goal is consistent absolute total return over varying market cycles.

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Market Neutral Income Fund returned 6.92% (Class I Shares at net asset value), strongly outperforming a -0.48% loss for the Bloomberg US Government/Credit Index and 0.05% increase for the Bloomberg Short Treasury 1-3 Month Index.

What factors influenced performance during the annual period?

The equity market posted strong results in response to Covid vaccination rollouts, positive economic data, fiscal stimulus and accommodative monetary policies. Despite the very strong equity market returns, the annual period saw pockets of elevated volatility during several events including the US presidential election, the Georgia Senate run-off elections, the storming of the US Capitol, the Covid vaccine rollout, commodity shortages, and supply-chain disruptions. These volatility pockets were conducive to the Fund's result despite declining volatility observed in the Cboe Volatility Index (VIX) (from 38.02 at the beginning of the period to 16.26 at the end).

The hedged equity strategy within the Fund benefited from strong S&P 500 Index performance given that the strategy's equity basket was able to participate in a portion of the market's upside, though constrained by the strike price of the portfolio's use of written calls. The pockets of volatility seen in the market also provided attractive option rebalancing opportunities, and the strategy benefited from a higher level of implied volatility in the options market. Moreover, the use of S&P 500 Index options in the strategy provided premium capture in addition to the dividends received from the equity basket.

The convertible arbitrage portion benefited from the pockets of volatility, which provided opportunities to profit from convertible hedge rebalancing. Additionally, an impressive $83.9 billion of new US convertibles were issued according to Bank of America. These new convertibles were attractive for convertible arbitrage as they were brought to the balanced portion of the market which, when combined with elevated

OVERVIEW

The Fund combines two complementary strategies with different responses to volatility: convertible arbitrage seeks alpha and uncorrelated returns, while hedged equity provides income from options writing and upside participation.

KEY FEATURES

ⁿ  Generates returns not dependent on interest rates, a key differentiator from traditional bond strategies.

ⁿ  Employs an absolute-return strategy with historically lower beta to fixed-income and equity markets as well as lower volatility and limited drawdowns.

ⁿ  As one of the first alternative mutual funds, capitalizes on more than four decades of experience in the convertible space.

PORTFOLIO FIT

The Fund may provide potential diversification, particularly in a low interest-rate environment.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Market Neutral Income Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

A note concerning Morningstar Ratings for Calamos Market Neutral Income Fund Morningstar recently sought to refine its categorization of alternative funds, splitting large heterogeneous categories into smaller, more-focused peer sets. Calamos applauds Morningstar's continuous commitment to improving investor understanding of mutual fund offerings. As of April 30, 2021, Morningstar assigned the Fund to a new category, Relative Value Arbitrage, a group of only eight funds. With such a small set of data points, Morningstar has determined that funds in this category will not be assigned a star rating. The Fund's move to the Relative Value Arbitrage category has no bearing on the management of the fund itself, nor was it made in response to a change in the management of the Fund.

volatility, increased opportunities for trade rebalancing (gamma capture). Much of the new issuance was also offered at a discount to the convertibles' theoretical valuations, providing an opportunity for pricing arbitrage.

A convertible bond may be thought of as the combination of a bond plus a call option. Although the rising-interest-rate environment was an impediment to the convertible's bond component, narrowing credit spreads more than offset the impact from rising rates. The 3-year US Treasury yield increased from 0.19% to 0.75%, the 5-year yield rose from 0.38% to 1.18%, and the 10-year yield jumped from 0.88% to 1.55%. According to Bloomberg, high-yield credit spreads narrowed by 209 basis points to 332 basis points over US Treasuries. Near-zero overnight interest rates were a headwind to the carry on the cash received from short positions (our custodian rebates us the fed funds rate less our roughly 35 basis points of borrowing costs).

The Fund also held small allocations in special purpose acquisition company (SPAC) arbitrage and merger arbitrage, which contributed positively to the annual period result.

In summary, the Fund benefited from the strong equity market performance, as the equity basket used in the hedged equity portion of the portfolio rose. Volatility provided attractive rebalancing opportunities for both the hedged equity and convertible arbitrage strategies. Robust convertible issuance and narrowing credit spreads provided attractive opportunities in convertible arbitrage. The above factors combined to create a favorable environment that allowed the Calamos Market Neutral Income Fund to post a consistent, positive return while similar risk investments (like bonds) were challenged during a period of rising and volatile interest rates.

How is the Fund positioned?

At the end of the annual period, the Fund had 43.0% in convertible arbitrage and 50.2% in hedged equity strategies. The allocation to convertible arbitrage was trimmed from 57.7% at the beginning of the annual period as we pared convertibles whose valuations had richened. We rebalanced these proceeds into the hedged equity strategy as volatility declined. Finally, the Fund had opportunistic positions in SPAC arbitrage (5.6%) and merger arbitrage (1.2%).

At the beginning of the annual period, the allocation to convertible arbitrage was near its 60% peak, which reflected soaring convertible issuance. Although issuance slowed late in the period, we continued to find many opportunities. We remain active in the new-issue and secondary markets, and we have replaced existing in-the-money convertibles with new convertible issues when possible. The weighted-average delta of the convertible arbitrage strategy is near the median of its historic range, although it is a bit lower than earlier in the period. We have been reducing our exposure to deep-in-the-money paper and have taken advantage of issuers' willingness to pay full prices to encourage the conversion of their bonds.

Calamos Market Neutral Income Fund's hedged equity strategy is currently positioned with a higher-than-typical hedge ratio. The higher the hedge ratio, the less exposure the Fund has to equity-market downside. Steadily declining realized and implied volatility and a strong bid in the markets for out-of-the-money puts have sustained cheapness in put spreads. Consequently, we have been adding more put spreads to the Fund's hedged equity book in addition to the outright long-put allocation we always maintain in the Fund.

Calamos Market Neutral Income Fund

Along with our primary strategies, the Fund also has the flexibility to invest opportunistically in SPACs, which are shell companies that raise money to acquire companies seeking to go public. The closing of the acquisition is called a de-SPAC process, at which point the SPAC is usually a small-cap equity. SPACs resemble convertible securities in many ways. The typical structure of a SPAC is a $10.00 unit issue that includes a five-year warrant struck at $11.50. We have seen the SPAC market grow briskly, which offers us another way to add value for Fund shareholders. There are many ways to invest in SPACs, and our use of SPACs is designed to support the Fund's historically lower-risk profile and steady returns. Drawing on our long-standing experience in convertible arbitrage, we are employing a SPAC arbitrage strategy at the margin of the portfolio, seeking positive returns with low risk. We are not investing in the volatile SPACs that often make headlines. In the same vein as how we seek to isolate cheap options in the Fund's convertible arbitrage strategy, we are using the SPAC structure to isolate cheap options with a risk profile that is similar to—and potentially even less risk than—our convertible arbitrage strategy. We're generally buying SPACs at $10.00 or less and trading out of them at $10.50 to $11.00, without adding a lot of equity sensitivity to the book.

What are your closing thoughts for Fund shareholders?

We believe that the Calamos Market Neutral Income Fund is well positioned for the current market environment. Fiscal and monetary policy uncertainties, including the potential for tax increases, more regulation, congressional spending, and the timing and magnitude of Federal Reserve tapering are likely to add market volatility. Moreover, the pandemic, potential for inflation, and political divides are likely to fuel volatility and market rotation.

As rising interest rates put pressure on traditional bond strategies, we believe Calamos Market Neutral Income Fund can provide especially compelling benefits as a fixed-income alternative. The Fund employs two complementary strategies—convertible arbitrage and hedged equity—to pursue absolute returns and income that is not dependent on interest rates.

Calamos Market Neutral Income Fund

ANNUALIZED RETURN: SINCE INCEPTION (5/10/00) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A, Class C and Class R6 shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Market Neutral Income Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.23%, Class C shares is 1.98%, Class I shares is 0.98% and Class R6 shares is 0.90%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Load-adjusted returns are adjusted for the maximum front-end sales load of 2.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The Bloomberg US Government/Credit Index is comprised of long-term government and investment-grade corporate debt securities and is generally considered representative of the performance of the broad US bond market. The Bloomberg Short Treasury 1-3 Month Index is generally considered representative of the performance of short-term money market investments and is provided to show how the Fund's performance compares to public obligations of the US Treasury with maturities of 1-3 months.

The Cboe Volatility Index (VIX) is a leading measure of market expectations of near-term volatility conveyed by S&P 500 Index (SPX) option prices.

The Morningstar Market Neutral Category represents funds that attempt to eliminate the risks of the market by holding 50% of assets in long positions in stocks and 50% of assets in short positions.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Hedged Equity Fund

OVERVIEW

The Fund blends a core long-equity portfolio with an actively managed option overlay. Tactical management creates opportunities to add alpha from option market dynamics and equity market volatility.

KEY FEATURES

ⁿ  Our investment approach is highly responsive to dynamic market conditions, unlike many less-active option-based strategies.

ⁿ  The investment team seeks to take advantage of opportunities the market presents, with a focus on being favorably positioned for as many outcomes as possible.

PORTFOLIO FIT

The Fund's options-based risk-management strategy can provide upside participation in equity markets while limiting downside exposure, thereby improving the quality of the ride.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS HEDGED EQUITY FUND

INVESTMENT TEAM DISCUSSION

Fund's Strategic approach and Role in Portfolio

Calamos Hedged Equity Fund's strategy blends a core long-equity portfolio with an actively managed options overlay. Tactical management creates opportunities to add alpha from option-market dynamics and equity-market volatility. The Fund seeks to take advantage of opportunities the market presents, focusing on being favorably positioned for as many outcomes as possible.

The Fund, which can serve as a core equity substitute, seeks to provide better upside/downside asymmetry than long-only equities and avoids using traditional investment products to dampen volatility on the equity sleeve. During the annual period, the Fund's investment approach was highly responsive to dynamic market conditions, a key differentiator compared to peers that utilized less actively managed option-based strategies.

How has the Fund performed?

True to its risk-managed design, Calamos Hedged Equity Fund participated in the equity market's upside with significantly less risk versus long-only equities—thanks to our hedging strategy. For the annual period, the Fund maintained an approximate beta of 0.51, which is in line with the historical beta of 0.49 since the Fund's inception versus the S&P 500 Index as of October 31, 2021.

For the 12 months ended on October 31, 2021 ("annual period"), Calamos Hedged Equity Fund gained 19.60% (Class I shares at net asset value) versus the S&P 500 Index increase of 42.91% and the Bloomberg US Aggregate Bond Index return of -0.48%. Since its inception on December 31, 2014, the Fund gained 7.34% on an annualized basis (Class I shares at net asset value) versus 14.70% for the S&P 500 Index and 3.07% for the Bloomberg US Aggregate Bond Index.

What factors influenced performance during the annual period?

Concerns about inflation, how the Fed might react, and the Covid delta variant are all variables that put market participants a bit on edge during the period. But the strength of the equity market, since its bounce off the March 2020 low, and the unprecedented market liquidity has market volatility measured by the Cboe Volatility Index (VIX) trading in the tame mid-teens, which allows the bulls to sleep better at night. If you look back over the last 41 years, the market typically has at least one intra-year drop of roughly 14%. In 2021 so far, the most profound decline has been less than 5%. All of the above factors add up to a more passive environment for the investment team. With market action over most of the period in market-up/volatility-down mode, it's theoretically more comfortable to add hedge and navigate.

Simply put, option prices cheapen when the market rises, and actual volatility is normalized or low. Adding a hedge is a lot easier in this type of volatility market. As long as earnings are robust, consumer demand continues to pick up, and central-bank policy remains easy, we have ample catalysts for hedging. These are all positives for continued equity growth. But there is a caveat; the forward volatility futures curve is elevated with July 2022 VIX Futures pricing a 24 VIX well above its historical mean of

Calamos Hedged Equity Fund

18.50, which tells us that options markets are currently pricing in or implying potentially violent moves well into 2022.

Along with concerns about inflation, how the Fed may react, and additional Covid negative surprises, the team is looking to layer in downside protection opportunistically and cost effectively. If actual volatility does catch up with implied volatility, we still want to be in the market, and a disciplined hedge on top of equity exposure can help us get the sleep we need. The higher volatility and skew* makes put and call spreads more appealing as we look to capture 45% to 55% upside and limit downside to 30% to 40%, ultimately driving better risk-adjusted returns to the Fund.

How is the Fund positioned?

The current landscape in the options market allows us to structure our hedge, emphasizing better performance on the tails. This positioning provides additional risk mitigation over and above our average 40% to 50% put notional minimum while also adding upside participation potential. The trade-off is a reduction in net income we receive from selling calls above our put cost. Given the Fund's defensive mandate in addition to the low volatility and high skew in the options market, we feel this trade-off is warranted and opportunistic. With the potential resurgence of market volatility, options pricing now allows us to sell call options at approximately 3% to 5% out of the money (OTM), representing more attractive price levels than the protective puts being purchased at about 5% OTM. This aligns with our traditional "North Star" trade mechanics of selling OTM calls versus buying OTM puts. We continue to use rallies to replace some of our put hedge with long put spreads, which appeared attractive during this move.

At the end of the annual period, the Fund's net put protection was 40%, with an average strike of 3817 on the S&P 500 Index (15% OTM). Our call positioning included a call write of 40%, gross short calls of -74% and gross long calls of 34%. Gross long calls were lower than in the past. At the end of the annual period and relative to the S&P 500 Index, our sector positioning was slightly overweight to the consumer discretionary and information technology sectors. The portfolio had slight underweight positioning to the materials, financials, consumer staples, real estate, and materials sectors. In terms of the Fund's market-capitalization positioning relative to the S&P 500 Index, the Fund maintained a heavier relative weight to larger-capitalization (>$25 billion) holdings and lighter weight to small and mid-capitalization ($1 to $25 billion) holdings.

What closing thoughts do you have for Fund shareholders?

As the equity markets challenge all-time highs, we have to be conscious of the fact that markets don't go straight up without a healthy decline now and then. Sometimes these downturns can enter correction territory (declines >10%), as we saw in Q1 of 2020, and sometimes they are less scary pullbacks (declines <10%). From the end of the Covid correction on March 23, 2020, to the date of this writing on October 31, 2021, the S&P 500 Index gained about 110%. During that time, the most significant decline has been less than 5%, within the expected intraday range of roughly 1.5%.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

*  Skew describes asymmetry from the normal distribution in a set of statistical data. Option skew is the difference in implied volatility between out-of-the-money options, at-the-money options, and in-the-money options. Volatility skew, which is affected by sentiment and the supply-and-demand relationship, provides information that helps fund managers determine whether to write calls or puts. The Cboe SKEW Index ("SKEW") is an index derived from the price of S&P 500 tail risk. Similar to the VIX, the price of S&P 500 tail risk is calculated from the prices of S&P 500 out-of-the-money options.

Calamos Hedged Equity Fund

With the latest earnings season winding down and vaccine efficacy rates at about 90%, we expect normalized volatility but acknowledge that equity markets could pick up volatility 20% to 30% higher well into 2022. This forecast makes us enthusiastic about our current positioning in the Hedged Equity Fund. Should equity markets advance, the Fund is poised to participate in its upside while also providing an enhanced income stream from well-positioned call spreads and our tracking portfolio's equity dividends. Conversely, should the markets retreat, the dividend income stream and the put protection used in the Fund will provide potential downside risk mitigation.

GROWTH OF $1,000,000: SINCE INCEPTION (12/31/14) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.22%, Class C shares is 1.97% and Class I shares is 0.97%.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown includes the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum frontend sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

The Bloomberg US Aggregate Bond Index is considered generally representative of the investment-grade bond market.

The Cboe Volatility Index (VIX) is a leading measure of market expectations of near-term volatility conveyed by S&P 500 Index (SPX) option prices.

The Cboe SKEW Index essentially tracks the willingness of investors to pay up for downside protection on the S&P 500 Index.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Phineus Long/Short Fund

CALAMOS PHINEUS LONG/SHORT FUND

INVESTMENT TEAM DISCUSSION

What is the essence of the investment approach?

Through a global long/short structure, the Fund invests in publicly listed equity securities. Components of the strategy include the following:

ⁿ  A fundamental global approach that blends top-down and bottom-up considerations. Company analysis is integrated with industry, thematic and macro research.

ⁿ  An inclusive framework for identifying potential returns and associated risks. The framework accounts for company, industry, style, country and market factors.

ⁿ  Flexible capital allocation allowing for all investment styles, market caps and geographic regions. The investment universe is global, liquid and scalable. Exposure levels and investment styles depend upon market conditions and the economic cycle.

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Phineus Long/Short Fund returned 38.69% (Class I shares at net asset value). The S&P 500 Index returned 42.91%, and the MSCI World Index gained 41.05% over the same period.

Since its inception on May 1, 2002, the Fund has returned 10.77% on an annualized basis (Class I shares at net asset value) and, thus, markedly outperformed both the S&P 500 and MSCI World Indexes, which returned 9.91% and 8.92%, respectively, over the same period. As of October 31, 2021, the long/short portion of the portfolio had a delta-adjusted* net-long position of approximately 55%.

What factors influenced performance over the annual period under review?

The most significant influence on Fund performance over the past 12 months occurred in November 2020, when breakthroughs in vaccine development encouraged hopes that the pandemic could be brought to a resolution in 2021. Style performance in the following months witnessed a historic rotation into value, cyclical and small-cap stocks. This rotation continued into May commensurate with a pickup in bond yields and upward earnings revisions for the cyclical cohort. The Fund enjoyed sharp outperformance during this period, reflecting our positioning in cyclical businesses with strong operating leverage; in many cases, these stocks had been compressed by the pandemic impact and, thus, benefited as vaccines drove a rapid reopening.

From May to August, investor nervousness brought on by the delta variant translated into a defensive mood that has benefited the health care and technology sectors, largely at the expense of the more cyclical and higher-beta plays. This comeback by one of the most characteristic trends of the post-2008 era was signaled by the decline of US Treasury yields. However, we believe this leadership should not be extrapolated,

OVERVIEW

The Fund seeks strong risk-adjusted and absolute returns across the global equity universe. The Fund uses a global long/ short strategy to invest in publicly listed equity securities.

KEY FEATURES

ⁿ  Fundamental global approach blends top-down and bottom-up considerations.

ⁿ  Flexible asset allocation allows for all investment styles, market caps and geographic regions depending on the market environment.

ⁿ  Comprehensive approach assesses stock, industry, style, country and market factors.

ⁿ  Knowledge-based industry concentration includes technology, communications, media, financials and health care.

PORTFOLIO FIT

The Fund seeks to provide strong risk-adjusted returns via an alternative solution that complements and diversifies a global or US equity allocation.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

*  Delta-adjusted basis measures the price sensitivity of an option or portfolio to changes in the price of an underlying security. Delta-adjusted basis exposure is calculated by Calamos Advisors LLC and is specific only to a point in time since a security's delta changes continuously with market activity.

Calamos Phineus Long/Short Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

and the Fund remains biased in favor of names perceived as the more cyclical and recovery positions.

The calendar quarter ended September 30, 2021, was dominated by conflicting narratives at the macro level. Peaking leading indicators of activity and declining US Treasury yields implied a moderating economic cycle and prompted a defensive mood. On the other hand, industrial production accelerated and should remain robust well into 2022. These crosscurrents reflect the unusual features of this cycle versus past precedents.

The summer rotation in favor of defensive and quality styles as well as the decline in US bond yields highlight investors' conviction that the stagnation of the past decade will persist. In contrast, we believe it is far too early to be positioning portfolios for "late cycle." And the Fund's positioning is anticorrelated to this consensus, partly because markets are already priced as if this outcome is certain and partly because the post-2008 era is unlikely to be a prologue for what comes next.

What helped and hurt performance over the annual period?

The Fund's largest contributors were long investments in the industrials and financials sectors, whereas short exposure in consumer discretionary and hedges on the SPDR S&P 500 ETF Trust hindered performance. Notable contributors during the period included long positions in an energy sector ETF 0.40% full-year average, Google 4.5%* (communication services), and Morgan Stanley 3.6%* (financials). Detractors included short positions in an S&P 500 ETF Trust -32.2%* (market hedge) as well as short positions in Tesla -2.04%, covered in June 2021 (consumer discretionary), and Costco -2.1%* (consumer staples).

How is the Fund positioned in the context of the global economic cycle?

Our broadest cyclical exposure is industrials and transports, and then financials; we avoid the more expensive consumer cyclicals (retailing) and longer-duration consumer equities (food and luxury). This bias toward the industrial portion of the economy reflects our view that industrial production has lagged, while real consumer incomes could be eroded by higher prices. Most consumption categories are above pre-Covid levels, yet this is less true of the production side of the economy, especially outside the US.

We view financials as the ideal hedge for a more reflationary outcome than many expect. Banks in particular are highly correlated with rising-inflation expectations. We also believe that the non-macro headwinds of the past decade—litigation, taxation and regulation—are largely behind the industry. The Fund has reduced exposure to those businesses more exposed to capital markets where upside is more limited from this point. However, the Fund is biased toward retail banks because they benefit from rising house prices and face less disintermediation risk. Abroad, UK banks are preferred over their continental peers, as the Bank of England is likely to raise rates more aggressively than the market expects.

We have traded the energy sector long through 2021; although we reduced our position in June, we repurchased at the lows in mid-August. Our exposure is isolated to the key beneficiaries of the structural underinvestment due to climate politics. We

*  10/31/21 % of NAV

Calamos Phineus Long/Short Fund

view the sector as a hedge against a more stagnant setting (more inflation, less growth) relative to what we expect. Oil demand estimates for 2022 are too low and the supply side is hampered by capital discipline and regulatory risk. Oil prices should be fundamentally supported, but the conundrum of robust spot prices combined with lower five-year forward prices gives us pause. We are intrigued by the robust free cash flow yields on both spot and forward oil price assumptions.

Although the broad themes across the portfolio have not changed, we were active at the stock level, favoring businesses that can navigate the ongoing recovery from the pandemic and, thus, produce material earnings leverage. If our assumption of sustained economic expansion is correct, the Fund's bias toward industrials and financials will prove rewarding.

Looking at the risks, it is hard not to focus on China. Evergrande is not a "Lehman moment" due to liquidity injections and the suppression of market-based pricing, while the government ownership of banks removes counterparty risk. Yet the Chinese economy is entering a long period of stagnation more akin to Japan in the 1990s than the US post-Lehman. With property accounting for about 25% of the economy, an extended slowdown seems inevitable.

China's woes underline the risk of viewing emerging markets (EM) as a single asset class. Of course, many investors do, and capital flows will inevitably come out of China and be reallocated to what are perceived as quality plays elsewhere in EM.

The Fund is underweight in non-US economies and non-US revenues and, thus, more levered to US domestic demand. This will inevitably shift when the US enters a sustained slowdown, perhaps later in 2022. For now, we struggle to allocate the long book outside the US as long as the opportunity set "closer to home" is robust.

What is your macro perspective heading into 2022?

The Fed's steps toward tapering have led many to assume the boom phase of the recovery has been foreshortened. Deceleration is built into any V-shaped recovery. We are entering the critical stage when the crutches of policy support drop away, and the private sector must pick up the baton and drive the expansion. The good news is that the US economy largely decoupled from the virus in late 2020, partly due to stimulus but also due to adaptability, and that learning curve has not been undone by the delta variant.

Corporate surveys highlight that the rate of order growth in production across much of the developed world remains strong. The primary source of economic moderation in the third quarter of 2021 has been the auto sector, which is the epicenter of supply bottlenecks. Demand outside autos has been robust and coincident with vibrant activity in the rest of the economy. These supply issues will begin to ease as much of the world reopens for business.

Most measures of production globally will accelerate as supply-chain disruptions ebb, though the supply chain may not completely normalize until the second half of 2022. New orders versus inventories are no longer extreme and delivery times are no longer lengthening, even for autos. Equities that benefit the most from supply shortages, such as haulage, shipping and auto-related semis are no longer outperforming.

The consensus is too bearish on the economic outlook for both the fourth quarter of 2021 and 2022. Fears of a fiscal cliff are overblown, partly because consumers have saved the vast bulk of their fiscal transfers. Excess savings from the pandemic will

Calamos Phineus Long/Short Fund

inevitably be converted into consumption, supported by the enormous gains in wealth of the past year, growing job security and fear of rising prices.

The post-2008 decade suffered from a chronic shortage of demand. Consumers were forced to deliver in the wake of the housing collapse, while the corporate sector had little incentive to invest. Circumstances today are starkly reversed. With a record number of job openings and firms struggling to fill them, the consumer is in a good position to replace fading stimulus with employment and higher wages.

Covid has been a decisive protagonist for risk assets, yet it can be viewed as incidental to the secular changes that have been building up for years. One major shift is the retreat of globalization, which is forcing risk assets into distinct regional regimes of governance and profitability. Unconventional policy prescriptions and the inevitable fruits of the long stagnation that pervaded the post-2008 decade are equally obscuring the horizon.

This is creating an unfamiliar but positive demand setting that coincides with a less-elastic supply of labor and intermediate goods. While the coronavirus is largely responsible for the constraints upon supply, the broader reassessment of global production chains in a world fracturing into regional economic zones is unlikely to be transitory.

We see the US 10-year Treasury yield rising to 1.8% by year end, though bond yields have not risen to the level implied by global Purchasing Managers' Indices due to the enormous interventions by the Federal Reserve. Since May, the Fed has purchased about 70% of Treasury issuance, but this will diminish as the Fed tapers. Pricing pressures will be persistent because they are increasingly driven by excess demand. All of this explains our reluctance to be overexposed to the equity derivatives of long duration.

Forecasting the degree and speed of the rise in rates is challenging. On the one hand, US rates reflect the global balance of inflation versus deflation risks more than any other sovereign debt market. As we write this note, the currency-hedged yield pickup in US Treasuries for German and Japanese investors is large, helping to limit the rise in US nominal yields and, in turn, suppressing real yields.

On the other hand, there are numerous reasons to believe that today's inflationary pressures are not as transitory as some imagine. The reversal of globalization is forcing companies to restore and assume greater control over supply chains. Other factors include a structural bull market in oil, higher housing costs, less labor supply due to deteriorating demographics, a rise in minimum wages, and the higher costs of the "environmental" component of ESG.*

Risk assets are well supported if credit conditions remain easy and the Fed stays pro-growth, but short-rate expectations appear too sanguine. For the moment, monetary conditions are abnormally loose, and by some measures looser than any point since the Global Financial Crisis. The real fed funds rate is still near 50-year lows, yet the US output gap will approach decade highs by 2023. This "best of all possible worlds" is unlikely to last beyond 2022.

For the past year, the news on corporate profitability has been stunningly positive. Although market action into September 2021 could be interpreted as a deterioration

*  ESG stands for Environmental, Social and Governance or the three pillars of sustainability. In a business context, sustainability refers to how well a company's business model contributes to enduring development.

Calamos Phineus Long/Short Fund

in the outlook, the key dynamic for equities will be a sustained rise in corporate earnings into 2023. As investors search for reasons to be cautious, we believe concern over earnings is premature as long as the momentum in nominal GDP is above trend, probably into mid-2022. Rising costs, either for intermediate inputs or labor, are an indication of persistent demand and should be manageable as long as revenue momentum is sufficient to allow margins to expand. The time to worry is when corporate managements enter an aggressive capital-investment cycle, but we are not there yet.

Our investment conclusion rests upon the observation that corporate and economic momentum will continue to be robust well into 2022. Although the monetary and positioning backdrop can pose difficulties at any stage of the cycle, today's historic setting argues for leaning into risk assets for as long as the fundamental momentum is apparent.

What are your closing thoughts for Fund shareholders?

Today's crosscurrents are preventing investors from looking beyond the pandemic. Many investors are concerned that the recovery is fully baked and are convinced that inflation, the pandemic, fiscal cliff, fed tapering and other factors will short circuit the recovery, returning the world to the essential characteristics of the post-2008 era.

The striking features of the market at the end of the third quarter in 2021—the decline in bond yields and rotation to defensive quality—were propelled by the conviction that the end of the economic recovery was in sight. To us, this underscores the depth of today's deflation psychology. It highlights the extent to which investors have become prisoners to the direction of bond prices.

While "stagflation" has become a popular term for the bears, it is possible that financial markets are signaling moderately higher inflation but also significantly higher economic growth. The latter is more analogous to the US experience of the 1950s than the stagflation of the 1970s. While the outcome will not be known for years, we see markets gravitating to the more sanguine of the two paths as the inflation data into 2022 proves tamer than feared.

The wave dynamics of Covid imply improvement for at least three to four months, but possibly beyond that as well. We believe the summer delta wave was the last significant one of the pandemic and might mark its conclusion. This would echo the pattern of the 1918/1919 flu and others that were characterized by four waves and lasted no more than two years. New treatments and infection penetration levels also support this view.

This final stretch of the pandemic and the uncertainly over inflation imply that long duration should be carefully managed within portfolios. We do not know how rapidly the supply constraints will ease as the world gradually overcomes the pandemic, but the secular and cyclical circumstances of today are unprecedented. Although the response by central banks will be slow and reluctant, the tide is just beginning to turn for interest rates in the developed world.

Fundamental momentum will remain above trend into 2022, and the positive productivity shock of the pandemic will linger for profits and economic growth. This will eventually wane under the weight of rising indebtedness, taxation and regulation. At some point, risk assets will fully discount recovery and instead start considering the challenge posed by the collapse of policy discipline.

Calamos Phineus Long/Short Fund

In the prosaic language of our industry, the pandemic has been the great wall of worry for risk assets to climb. As long as it dominates, the bull market is not under threat. As we progress through 2022, the mood of central banks will begin to shift more decisively. At some point, the economic context will be defined by negative growth surprises and positive inflation surprises.

But we are not there yet. The bullish dynamic that underpins US dollar-based risk assets is "unfinished business."

ANNUALIZED RETURN: SINCE INCEPTION (5/1/02) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

The performance shown for periods prior to April 6, 2016 is the performance of a predecessor investment vehicle (the "Predecessor Fund"). The Predecessor Fund was reorganized into the Fund on April 6, 2016, the date upon which the Fund commenced operations. On October 1, 2015, the parent company of Calamos Advisors, purchased Phineus Partners LP, the prior investment adviser to the Predecessor Fund ("Phineus"), and Calamos Advisors served as the Predecessor Fund's investment adviser between October 1, 2015 until it was reorganized into the Fund. Phineus and Calamos Advisors managed the Predecessor Fund using investment policies, objectives, guidelines and restrictions that were in all material respects equivalent to those of the Fund. Phineus and Calamos Advisors managed the Predecessor Fund in this manner either directly or indirectly by investing all of the Predecessor Fund's assets in a master fund structure. The Predecessor Fund performance information has been adjusted to reflect Class A, Class C and Class I shares, expenses. However, the Predecessor Fund was not a registered mutual fund and thus was not subject to the same investment and tax restrictions as the Fund. If it had been, the Predecessor Fund's performance may have been lower.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Phineus Long/Short Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 2.94%, Class C shares is 3.67% and Class I shares is 2.67%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares. Returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graph does not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

The MSCI World Index (US Dollars) is a market-capitalization weighted index composed of companies representative of the market structure of developed market countries in North America, Europe and the Asia/Pacific region.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Convertible Fund

OVERVIEW

The Fund invests primarily in convertible securities of US companies that are diversified across market sectors and credit quality.

KEY FEATURES

^◼  Leverages more than four decades of research and experience in convertible security investing.

^◼  Provides diversification across market sectors and credit quality, emphasizing midsize companies with higher-quality balance sheets.

^◼  Seeks to provide upside participation in equity markets with less exposure to downside than an equity-only portfolio over a full market cycle.

^◼  Takes environmental, social and governance (ESG) factors into account, evaluating whether they impact a company's cash flow, risk profile and long-term returns.

PORTFOLIO FIT

When used in conjunction with an equity allocation, the Fund offers a potential way to manage risk by employing securities that engage in upside equity movements with limited downside participation.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS CONVERTIBLE FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Convertible Fund had a positive return of 27.40% (Class I shares at net asset value) versus the ICE BofA All US Convertibles Index (VXA0) increase of 32.95%. For the same period, the S&P 500 Index gained 42.91%.

Since its Class I shares inception on June 25, 1997, the Fund returned 9.25% on an annualized basis compared with an annualized gain of 9.31% for the ICE BofA All US Convertibles Index and an 9.03% annualized return for the S&P 500 Index.

What factors influenced performance during the annual period?

The equity and convertible markets posted very strong results during the period, responding well to the Covid vaccination rollout, positive economic data, fiscal stimulus and accommodative monetary policies. The Fund's performance was driven in part by its exposure to technology issuers whose products facilitate working, playing, learning and shopping from home as well as those companies offering the support services—such as cloud computing, internet security and e-payments—to make it all happen. These businesses saw demand for and adoption of their products and services accelerate at breakneck speed as people the world over were forced to communicate remotely. In addition, the Fund benefited by including cyclical companies, such as cruise lines, restaurants, airlines, retailers and live-event providers, well poised to participate in the economic recovery as Covid numbers continued to drop, and expectations for "getting back to normal" at last seemed palpable near the end of the period.

Along with strong performance, the convertible and equity markets worked through periods of higher volatility. The annual period included the presidential election, a run-off election in Georgia impacting Congressional leadership, volatile interest rates, the storming of the US Capitol, the vaccine rollout, the Covid delta variant, commodity shortages, supply-chain disruptions, and rising inflation. As these events created pockets of elevated volatility, our preference has been to focus on convertibles with balanced risk/reward attributes and to be underweight the most equity-sensitive convertibles, which generally lack favorable downside mitigation. This underweight to equity-sensitive convertibles held back the relative return as these issues performed similarly to the overall equity market. (Equity-sensitive convertibles were up 53.5% during the annual period as measured by the ICE BofA Equity Alternative US Convertible Index.) Convertibles with more balanced risk/reward profiles were up 27.0% (as measured by the ICE BofA Total Return US Convertible Index), while those convertibles displaying more credit sensitivity were up 16.0% (per the ICE BAML Yield Alternative US Convertible index).

From an economic sector attribution perspective, the Fund benefited most from its average underweight position and selection in the financials sector. An average underweight and selection within the health care sector as well as an underweight allocation to the utilities sector also supported the period result. In financials, the Fund benefited from strong selection in the diversified banks, consumer finance and asset management & custody banks industries. In health care, strong performance was noted

Calamos Convertible Fund

in life science tools & services as well as health care technology. In general, names that exhibited better risk/reward profiles underperformed the most equity-sensitive convertibles whose downside mitigation is deficient, specifically within information technology (application software, data processing & outsourced services and intranet services & infrastructure) and industrials (trucking, airlines, and industrial machinery).

How is the Fund positioned?

Our focus in positioning the Calamos Convertible Fund's portfolio is to optimize the portfolio's risk/reward tradeoff by providing more exposure to upside in the equity markets than potential downside. We seek companies that are growing their intrinsic value and whose fundamentals are strengthening. The portfolio is positioned with slightly lower equity sensitivity than the benchmark index but has a more favorable risk/reward profile. The portfolio's largest exposures include growth-focused sectors, such as information technology and consumer discretionary, where we are finding secular opportunities in cloud computing, internet security, e-payments, e-commerce and many others supporting "at-home" trends that accelerated during the pandemic. We believe there are also strong cyclical opportunities that can perform well as consumers drive the next leg of economic expansion. These span multiple industries, including airlines, cruise lines, retail, entertainment and semiconductors. The portfolio's largest relative underweight exposures are to more defensive areas, such as the financial sector where we believe convertible structures are less attractive.

New convertible issuance was robust during the annual period, as $153.3 billion came to market globally with $83.9 billion introduced in the US. For some perspective, both of these amounts were larger than the full calendar year periods dating back to 2008. The new issuance expanded the convertible universe and provided an opportunity for us to rebalance the portfolio into convertibles displaying more attractive risk/reward profiles. The improved risk/reward should enable the Fund to participate in a diverse pool of equity upside with less susceptibility to downside corrections and volatile periods. In actively managing the portfolio, we have taken advantage of these periods by repositioning the portfolio into structurally stronger risk/reward convertibles. For example, we sold convertibles that have moved up and exhibit pure equity-like characteristics (with limited downside mitigation) or we have sold those that have moved down and exhibit pure credit-like characteristics (with limited upside potential). We believe this continual portfolio restructuring creates the best opportunity for achieving solid risk-adjusted returns over the long-term.

What closing thoughts do you have for Fund shareholders?

We maintain a positive outlook on the convertible securities market based on the broad economic recovery combined with a fundamentally attractive issuer base. The $153.3 billion in convertibles brought to market globally during the annual period were issued by companies seeking capital to take advantage of opportunities for growth, expansion, mergers, and increased research and development. We are excited by this broadening of the convertible market, which included a healthy mix of innovative companies—including established convertible market issuers and those issuing convertibles for the first time.

We expect that the economy's underlying strength will lead the Federal Reserve to taper its unprecedented levels of stimulus in the coming months. Although this has the potential to add short-term volatility to the markets, we anticipate any changes

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Convertible Fund

will be well communicated in advance, and overall policy will remain accommodative on a historical basis. We believe policy decisions will continue to be made with the goal of avoiding restrictive outcomes that could cut off economic expansion prematurely.

Our view is that the economy is expanding, but not overheating, and will ultimately transition from early expansion to a mid-cycle growth phase. This likely means heightened volatility for the foreseeable future as market participants scrutinize each data point through the transition. However, an environment of real growth with moderate inflation could be a very attractive backdrop for risk assets, including convertibles.

In closing, we believe the fundamentals of the convertible market remain strong. Continued volatility and rotations within the financial markets may occur but are not uncommon as the economy transitions toward the next phase of expansion. We believe the strategic case for investing in convertibles to help navigate this volatility without sacrificing upside participation remains intact.

ANNUALIZED RETURN: SINCE INCEPTION (6/25/97) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Convertible Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.14%, Class C shares is 1.89% and Class I shares is 0.89%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Load-adjusted returns are adjusted for the maximum front-end sales load of 2.25% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income of taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The ICE BofA All US Convertibles Index is comprised of approximately 700 issues of only convertible bonds and preferreds of all qualities. Since inception data for the index is shown from 6/30/97, since data is only available for full monthly periods.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

Due to their structural complexities, the attributes of convertibles may vary. Therefore, they are typically categorized as Yield Alternatives represented by the US CV Index (VYLD), Total Return Alternatives represented by the US CV Index (VTOT), or Equity Alternatives represented by the US CV Index (VEQU).

The ICE BofA Total Return US Convertibles Index is a subset of ICE BofA All US Convertibles Index including securities with a delta greater than or equal to 0.4 and less than 0.8 (VTOT).

The ICE BofA Yield Alternative US Convertibles Index (VYLD) is a subset of ICE BofA All US Convertibles Index including securities with a delta less than 0.4 (exhibiting bond-like characteristics).

The ICE BofA Equity Alternative US Convertibles Index (VEQU) is a subset of ICE BofA All US Convertibles Index including securities with a delta of 0.8 and greater (exhibiting stock-like characteristics).

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Global Convertible Fund

OVERVIEW

The Fund invests in global convertible securities, striving to balance risk/reward while providing growth and income.

KEY FEATURES

^◼  Provides broadly diversified exposure to the global convertible bond universe.

^◼  Leverages more than 40 years of research in convertible security investing.

^◼  Seeks to provide upside participation in equity markets with less exposure to downside than an equity-only portfolio over a full market cycle.

^◼  Blends global investment themes and fundamental research via active management.

^◼  Takes environmental, social and governance (ESG) factors into account, evaluating whether they impact a company's cash flow, risk profile and long-term returns.

PORTFOLIO FIT

Consisting of convertible securities that can participate in upside equity movements with potentially limited downside exposure, the Fund can provide a means to manage risk in conjunction with an equity allocation. The Fund can also serve a role within a fixed-income allocation, as convertibles have performed well during periods of rising interest rates and inflation.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS GLOBAL CONVERTIBLE FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Global Convertible Fund returned 19.09% (Class I shares at net asset value) versus the Refinitiv Global Convertible Bond Index return of 22.18%. We believe balanced convertibles offer the most attractive investment opportunity, given their combination of upside potential and downside resilience. This approach led us to underweight the most equity-sensitive and credit-sensitive convertibles in favor of those with balanced risk/reward attributes. Although equity-sensitive convertibles outperformed balanced convertibles during the period, we believe the Fund's longer-term performance affirms the wisdom of this strategy. Since its inception on December 31, 2014, the Fund increased 9.67% (Class I shares at net asset value) annualized versus a 9.12% gain for the Refinitiv Global Convertible Bond Index.

What factors influenced performance during the annual period?

The global equity and convertible markets responded well to the Covid vaccination rollout, positive economic data, fiscal stimulus and accommodative monetary policies and posted very strong period results (+22.18% Refinitiv Global Convertible Bond Index; +41.05% MSCI World Index). The Fund was well positioned for Covid-related themes, as it contained a heavy representation in technology issuers whose products and services allowed people to work, learn, shop, entertain and receive medical attention at home during the pandemic. In addition, the portfolio also included cyclical companies well poised to participate in the recovery and reopening including cruise lines, airlines and retailers.

New convertible issuance was robust during the period, as $153.3 billion of convertibles were issued globally. The new issuance expanded the convertible universe and provided an opportunity to rebalance convertibles that had become too equity sensitive with those that have more attractive risk/reward profiles. Our preference for these balanced convertibles led us to be relatively underweight to the most equity-sensitive areas of the convertibles market. Despite the very strong overall period result, the underweight allocation to the most equity-sensitive convertibles held back the relative return. Within the Refinitiv Global Convertible Bond Index, convertibles with more than 80% equity sensitivity rose 38.8% and strongly outperformed convertibles with balanced risk/reward attributes (40%—80% equity sensitivity; +19.5%) and convertibles with more credit sensitivity (<40% equity sensitivity; +7.9%).

From an economic sector attribution perspective, the Fund benefited most from strong security selection in the industrials sector as our holdings in the airlines industry outperformed. Security selection in energy added value, aided by the strong performance of names in the oil & gas exploration & production industry. An underweight allocation to the lagging utilities industry was also supportive to the portfolio result. Areas that most detracted from performance included materials, information technology and consumer discretionary. Within materials, an underweight allocation and security selection, notably in the steel industry, held back the relative return. In information technology, the relative return was hindered by security selection

Calamos Global Convertible Fund

in the internet software & services and application software industries. In consumer discretionary, holdings in the internet & direct market retail industry underperformed.

From a geographic perspective, the Fund benefitted from favorable security selection in Japan and Emerging Asia. Similarly, an underweight allocation in Europe lifted Fund performance. Security selection in the United States and Emerging Latin America held back the relative result.

How is the Fund positioned?

Our focus is to optimize the portfolio's risk/reward tradeoff by providing more exposure to upside in the equity markets than potential downside. As of the end of the annual period, the portfolio is positioned with slightly lower equity sensitivity than the benchmark index but with a more favorable risk/reward profile. In other words, we are overweight convertibles with the most balanced attributes versus the benchmark and also significantly underweight to convertibles displaying the most equity sensitivity. We seek to identify companies that are growing their intrinsic value through all market conditions and those whose fundamentals are strengthening.

From a sector perspective on an absolute basis, the largest portfolio weights reside in information technology and consumer discretionary, whereas energy and consumer staples represent the smallest absolute sector weights. Relative to the benchmark, the portfolio is most overweight to information technology and real estate whereas utilities and materials are significant underweights.

From a regional standpoint, the portfolio's largest weights are in the United States and Europe. Canada and Emerging Europe and South Africa represent the smallest absolute regional weights. We maintain relative overweight positions in Emerging Asia and Japan and underweight positions in Europe and the United States. These relative weights are due to bottom-up considerations as opposed to a macro call.

What closing thoughts do you have for Fund shareholders?

The global economy experienced an extraordinary recovery, and a moderation of economic growth and consumer optimism is not surprising. We still see strong corporate balance sheets, improving margins and spending on capital expenditures. The risks of Covid persist, but we remain hopeful in light of global vaccination efforts and promising emerging treatments. While we can never rule out a policy mistake, we expect the world's central banks will pursue a gradual course that should continue to support economic growth and, in turn, provide tailwinds for the stock market.

We expect the global economy to continue normalizing in the context of getting back to activities that had been restricted due to Covid. However, this return to normalcy will likely be accompanied by a moderation in the economy. In the United States, for example, this means GDP normalizes to a healthy 2% real GDP growth rate from the much higher bounce-back levels of the past year. The resulting strong nominal GDP will be good for top-line growth and has historically been good for earnings, if costs don't get out of line.

As growth moderates to a more typical pace, we expect inflation to follow suit. This may take a bit of time to play out, but we still believe it will occur in quarters rather than years. Although supply shortages and rising rates are at the forefront of investors' minds, debt levels, demographics and technology are all still powerful deflationary forces.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Global Convertible Fund

The Federal Reserve may not be refilling the punch bowl as quickly as it once did, but it does not seem likely to take away the bowl any time soon. Even if short-term rates rise from 0% to 1%, monetary policy is still quite accommodative. Combined with good earnings growth, this accommodative policy should propel equities higher, with convertible securities participating in the upside.

We believe the Calamos Global Convertible Fund is well positioned with risk/reward characteristics that offer an attractive balance of upside equity participation potential and equity risk mitigation. The Fund's level of equity sensitivity is a bit below that of the overall global convertible market, but we believe this level is appropriate given the importance we place on managing downside risk.

GROWTH OF $1,000,000: SINCE INCEPTION (12/31/14) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.35%, Class C shares is 2.10% and Class I shares is 1.10%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown includes the effects of an expense reimbursement that improved results and was in effect until October 31, 2020. Load-adjusted returns are adjusted for the maximum frontend sales load of 2.25% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The Refinitiv Global Convertible Bond Index (USD) is designed to represent the global convertible market.

Unmanaged index returns assume reinvestment of any and all distributions and, unlike fund returns, do not reflect fees, expenses or sales charges. Investors cannot invest directly in an index.

Calamos Timpani Small Cap Growth Fund

CALAMOS TIMPANI SMALL CAP
GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Timpani Small Cap Growth Fund posted a return of 50.80% (Class I Shares at net asset value), outperforming the gain of 38.45% for the Russell 2000 Growth Index.

Since Class I shares inception on March 23, 2011, the Fund has returned 16.80% on an annualized basis, while the Russell 2000 Growth Index returned 12.53% over the same period. We believe these comparisons demonstrate the Fund's ability to outdistance its benchmark over full market cycles.

What factors influenced performance during the annual period?

As indicated by the performance figures, the US equity markets enjoyed a very strong annual period for risk assets. For the annual period, companies enjoyed record corporate earnings as businesses benefited from a re-opening economy, stimulative policy and strong consumer spending. Markets started the annual period with a strong move upward, as investor enthusiasm was lifted by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets broadly favored small-cap stocks as well as reopening trades and more value-oriented stocks. This investor enthusiasm toward recovery stocks and value stocks stemmed from recognition that businesses in travel, leisure, restaurants, energy and financials all presented opportunities for the most significant rebound from the negative impacts of the economic and social shutdowns. Near the middle of the annual period, secular growth businesses came back in relative favor as investors turned attention back toward businesses that might be able to generate high and sustainable growth without relying on the benefit of a reopening economy. The specter of additional shutdowns from the delta wave of Covid in addition to the loftier valuations associated with recovery trades and value stocks cooled the relative appeal of those areas.

The Fund was able to generate strong absolute and relative performance due in part to investors' "risk-on" sentiment at the beginning the period but owes its better relative performance to a few key factors: First, the Fund had purposefully added to cyclical growth opportunities prior to the start of the annual period, as our analysis revealed that companies in this space possessed underestimated growth based upon market consensus and market pricing. Second, the portfolio management team continued to focus on businesses that, in our view, had better growth potential in both cyclical and more secular, or long-term, growth businesses. Because the market tends to extrapolate current dynamics into the future, the team was able to capitalize on short-term market concerns that afforded entry points in strong secular growth areas, such as software, which benefitted relative performance. For the annual period, small-cap value stocks handily outperformed small-cap growth stocks, as evidenced by the Russell 2000 Value Index's 64.30% return handily beating the Russell 2000 Growth Index's 38.45% gain. As mentioned, the Fund outperformed the Russell 2000 Growth Index by 1,235 basis points, largely due to the focus on strong and sustainable growth combined with underestimated growth.

OVERVIEW

The Fund invests in the equity securities of small-capitalization companies with high, sustainable growth potential, which may exceed market expectations.

KEY FEATURES

ⁿ  Combines fundamental research with the analysis of market estimates to identify the underestimated growth differential between a company's business strength and market expectations of that strength.

ⁿ  Pursues active management in a less-followed investment space.

ⁿ  Analyzes secular trends to uncover exploitable investment opportunities specific to small-cap companies.

PORTFOLIO FIT

Investing in small-cap companies is an important component of a diversified investment strategy. Smaller companies tend to experience greater growth and outperform larger companies.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Timpani Small Cap Growth Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Leadership within the small-cap growth market was represented by a mix of cyclical and secular growth areas for the annual period. Within the Russell 2000 Growth Index, the smaller energy sector (less than 1% of the index on average over the course of the reporting period) led the market with a 185% gain. Industrials (+61%), information technology (+55%), consumer discretionary (+52%), real estate (+49%) and financials (+46%) also all outperformed the growth index. Utilities (+38%), materials (+38%), consumer staples (+32%), communication services (+31%) and health care (+14%) all lagged behind the benchmark's performance.

Security selection and an underweight to the lagging health care sector were each additive to relative performance. Although health care was the worst-performing sector within the Russell 2000 Growth Index, the Fund's health care names collectively outperformed the Russell 2000 Growth Index's return for the period. Holdings in biotechnology, health care technology, pharmaceuticals, and life science tools & services each added significant value. Stock selection within information technology also boosted relative performance, with notable contributions from semiconductors and application software holdings.

Selection within communication services lagged that of the overall market, causing the sector to be a relative detractor. Disappointments within the movies & entertainment industry as well as the advertising industry led to the relative underperformance. The financials sector was also a relative hindrance to Fund performance over the period as selection lagged that of the market, and the Fund was underweight during intervals of strength for the sector. Fund holdings in insurance brokers and regional banks also held back relative performance.

How is the Fund positioned?

We continue to invest in both long-term secular-growth stocks and certain cyclical growth stocks that should benefit meaningfully from a continued economic uptick. A noteworthy portfolio change we made later in the annual period was decreasing our weighting in consumer discretionary stocks. This had been an area of greater emphasis, but given the continued macro murkiness tied to Covid and supply-chain disruptions, we reduced the Fund's exposure but remain overweight relative to the benchmark. We also increased our investment in technology stocks, especially certain software stocks that are riding upon strong secular trends. In addition, we increased our investment in energy holdings, moving from an underweight to an overweight at the end of the period, with notable interest in sustainable energy businesses.

What closing thoughts do you have for Fund shareholders?

The outlook remains bright for the small-cap growth asset class. Fundamentals are strong and valuations relative to large caps are low by most measures. History shows when relative valuations get to these levels, the probability of small-cap outperformance over the next annual period is high and can be meaningful. Additionally, we believe we are only one year into a sustained, multi-year leadership role for small caps. We continue to have an abundance of ideas for the portfolio and have seen increased M&A activity within the space. While we are always happy to own names that are acquired at a premium to their then current price, we also view this as strong indication that the combination of growth and valuation are also attractive to outside buyers.

Calamos Timpani Small Cap Growth Fund

ANNUALIZED RETURN: SINCE INCEPTION (3/23/11) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A, Class C and Class R6 shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Timpani Small Cap Growth Fund

GROWTH OF $1,000,000: SINCE INCEPTION (3/23/11) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.40%, Class I shares is 1.16% and Class R6 shares is 1.09%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023, to the extent necessary so that Total Annual Fund Operating Expenses of Class A, Class C and Class I shares are limited to 1.30%, 2.05%, 1.05% of average net assets, respectively. The Fund's investment adviser has contractually agreed to limit the Fund's annual ordinary operating expenses for Class R6 shares (as a percentage of average net assets) to 1.05% less the Fund's annual sub-transfer agency ratio (the aggregate subtransfer agency fees of the Fund's other share classes divided by the aggregate average annual net assets of the Fund's other share classes). For purposes of these expense limitations, operating expenses do not include taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective share class's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares.

NOTES:

Effective as of the close of business on May 31, 2019, the Fund acquired all of the assets, subject to the liabilities, of the Timpani Small Cap Growth Fund (the "Predecessor Fund") through a tax-free reorganization (the "Reorganization"). Pursuant to the Reorganization of the Predecessor Fund into the Fund, Class Y shareholders of the Predecessor Fund received Class A shares of the Fund, and Service Class and Institutional Class shareholders of the Predecessor Fund each received Class I shares of the Fund. As a result of the Reorganization, the Fund adopted the performance and financial history of the Predecessor Fund. Accordingly, the performance shown in the average annual total return table above for periods prior to the commencement of the Fund's operations on June 1, 2019 is the performance of the Predecessor Fund. The Fund has the same investment objective, strategy and portfolio manager as the Predecessor Fund. As a result, the performance of the Fund would have been substantially similar to that of the Predecessor Fund.

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The Russell 2000 Growth Index is a composite of small-cap companies located in the US that also exhibit a growth probability.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Timpani SMID Growth Fund

CALAMOS TIMPANI SMID GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Timpani SMID Growth Fund posted a return of 47.46% (Class I Shares at net asset value), outperforming the 37.12% gain for the Russell 2500 Growth Index.

What factors influenced performance during the annual period?

As indicated by the performance figures, the US equity markets enjoyed a very strong annual period for risk assets. For the full annual period, companies enjoyed record corporate earnings as businesses benefited from a reopening economy, stimulative policy and strong consumer spending. Markets started the period with a strong move upward, as investor enthusiasm was lifted by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets broadly favored small-cap stocks as well as reopening trades and more value-oriented stocks. This investor enthusiasm toward recovery stocks and value stocks stemmed from the recognition that businesses in travel, leisure, restaurants, energy and financials all presented opportunities for the most significant rebound from the negative impacts of the economic and social shutdowns. Near the middle of the annual period, secular growth businesses came back in relative favor as investors turned attention back toward businesses that might be able to generate high and sustainable growth without relying on the benefit of a reopening economy. The specter of additional shutdowns from the delta wave of Covid in addition to the loftier valuations associated with recovery trades and value stocks cooled the relative appeal of those areas.

The Fund was able to generate strong absolute and relative performance due in part to investors' "risk-on" sentiment at the beginning the period, but the Fund owes its better relative performance to a few key factors. First, the Fund had purposefully added to cyclical growth opportunities prior the start of the annual period, as our analysis revealed that companies in this space possessed underestimated growth based upon market consensus and market pricing. Second, the portfolio management team continued to focus on businesses that, in our view, had better growth potential in both cyclical and more secular, or long-term, growth businesses. Because the market tends to extrapolate current dynamics into the future, the team was able to capitalize on short-term market concerns that afforded entry points in strong secular growth areas, such as software, which benefitted relative performance. For the full annual period, small-cap value stocks handily outperformed small-cap growth stocks, as evidenced by the Russell 2500 Value Index's 58.15% return handily beating the Russell 2500 Growth Index's 37.13% gain. As mentioned, the Fund outperformed the Russell 2500 Growth Index by 1,034 basis points largely due to the focus on strong and sustainable growth combined with underestimated growth.

Leadership within the small-cap growth market was represented by a mix of cyclical and secular growth areas for the annual period. Within the Russell 2500 Growth Index, the smaller energy sector (less than 1% of the index on average over the course of the annual period) was the market leader with a 151% gain. In addition, industrials (+55%), real estate (+51%), information technology (+51%), consumer discretionary

OVERVIEW

The Fund invests in the equity securities of small- and mid-capitalization (SMID) companies with high, sustainable growth potential, which may exceed market expectations.

KEY FEATURES

ⁿ  Combines fundamental research with the analysis of market estimates to identify the underestimated growth differential between a company's business strength and market expectations of that strength.

ⁿ  Pursues active management in a less-followed investment space.

ⁿ  Analyzes secular trends to uncover exploitable investment opportunities specific to small- and mid-cap companies.

PORTFOLIO FIT

Investing in SMID companies is an important component of a diversified investment strategy. Small-to-midsize companies tend to experience greater growth and outperform larger companies, yet this greater potential also raises the potential for greater volatility—which is why we believe active management is crucial.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Timpani SMID Growth Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

(+47%) and financials (+46%) each outperformed the index. Utilities (+27%), materials (+26%), health care (+17%), communication services (+16%) and consumer staples (+8%) all lagged behind the benchmark's performance.

Overall, both security selection and sector weightings were additive to relative performance for the annual period. Security selection within information technology boosted Fund performance as holdings in the portfolio dramatically outperformed those of the Russell 2500 Growth Index. Strong issue selection within semiconductors, application software, and internet services and infrastructure each added considerable value. Stock selection and an overweight to the industrials sector also contributed to relative performance. Fund holdings within environmental and facility services, electrical components and equipment, and construction machinery each experienced strong performance, which was additive to the Fund's outperformance.

The consumer discretionary sector was a relative detractor of performance. Stock selection within the consumer discretionary sector detracted from relative performance, although the Fund's overweight to the outperforming sector was additive. Fund holdings within the casinos and gaming industry and the specialty stores industry set back relative performance. Stock selection within communication services and the Fund's modest overweight to the communication services sector were also detrimental to relative performance.

How is the Fund positioned?

We continue to invest in both long-term secular growth stocks and certain cyclical growth stocks that should benefit meaningfully from a continued economic uptick. A noteworthy portfolio change we made later in the annual period was decreasing our weighting in consumer discretionary stocks. This had been an area of greater emphasis but given the continued macro murkiness tied to Covid and supply chain disruptions, we reduced the Fund's exposure but remain overweight relative to the benchmark. We also increased our investment in technology stocks, especially certain software stocks that are riding on strong secular trends. In addition, we increased our investment in energy holdings, moving from an underweight to an overweight at the end of the period, with notable interest in sustainable energy businesses.

What closing thoughts do you have for Fund shareholders?

The outlook remains bright for the asset class. Fundamentals are strong, and valuations relative to large caps are low by most measures. History shows when relative valuations get to these levels, the probability of small-cap outperformance over the next annual period is high and can be meaningful. Additionally, we believe we are only one year into a sustained, multi-year leadership role for small caps. We continue to have an abundance of ideas for the portfolio and have seen increased M&A activity within the space. While we are always happy to own names that are acquired at a premium to their then current price, we also view this as strong indication that the combination of growth and valuation are also attractive to outside buyers.

Calamos Timpani SMID Growth Fund

GROWTH OF $1,000,000: SINCE INCEPTION (7/31/19) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 2.45%, Class I shares is 2.25% and Class R6 shares is 2.25%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses of Class A shares and Class I shares are limited to 1.35% and 1.10% of average net assets, respectively. The Fund's investment adviser has contractually agreed to limit the Fund's annual ordinary operating expenses for Class R6 shares (as a percentage of average net assets) to 1.10% less the Fund's annual sub-transfer agency ratio (the aggregate subtransfer agency fees of the Fund's other share classes divided by the aggregate average annual net assets of the Fund's other share classes). For purposes of these expense limitations, operating expenses do not include taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective share class's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares.

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The Russell 2500 Growth Index measures the performance of the small to mid-cap growth segment of the US equity universe. It includes those Russell 2500 companies with higher growth earning potential. The Russell 2500 Growth Index is published and maintained by FTSE Russell.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Growth Fund

OVERVIEW

A broad, flexible strategy enables the Fund to invest in the equities of US companies across all market capitalizations and sectors in order to attain the best potential for long-term capital growth.

KEY FEATURES

ⁿ  Seeks to provide attractive returns through an emphasis on higher-growth US companies spanning the full range of market capitalizations and sectors. Draws on more than three decades of experience in growth investing.

ⁿ  The portfolio reflects top-down, secular thematic views along with high-conviction, fundamentally researched stocks of companies with advantaged business models, high returns on capital, solid free-cash-flow generation, and stewardship-minded management.

ⁿ  Combines secular and cyclical growth to help manage the dynamics of the economy.

PORTFOLIO FIT

May be an attractive option for investors seeking higher growth and diversification that spans all caps of US companies across sectors and industries.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Growth Fund returned 46.40% (Class I Shares at net asset value), outperforming the S&P 1500 Growth Index return of 45.07%. By way of comparison, the broad equity market, as measured by the S&P 500 Index, advanced with a return of 42.91% for the same period.

Since Class I shares inception on September 18, 1997, the Fund has returned 12.49% on an annualized basis. The S&P 1500 Growth Index, the primary benchmark, returned 9.81% over the same period, and the S&P 500 Index returned 8.80%. We believe these comparisons demonstrate the Fund's ability to outpace the growth and broad indices over full market cycles.

What factors influenced performance over the annual period?

As indicated by the performance figures, the US equity markets enjoyed a very strong 12-month period for risk assets. For the annual period, companies enjoyed record corporate earnings as businesses benefited from a reopening economy, stimulative policy and strong consumer spending. Markets started the period with a strong move upward, as investor enthusiasm was lifted by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets favored reopening trades, recognizing businesses that had the opportunity to rebound most from the negative impacts of the economic and social shutdowns, notably in travel, leisure, and restaurants as well as the energy and financials sectors more broadly. Near the middle of the annual period, secular growth businesses caught favor as investors turned their attention back to businesses that might be able to generate high and sustainable growth without relying on the benefits of a reopening economy.

The Fund benefitted from adjusting the portfolio to increase cyclical growth names earlier in the annual period and then shifting more investment toward secular growth later in the annual period. For the annual period, growth stocks and value stocks had similar returns, as noted by the S&P 1500 Growth Index return of 45.07% compared with the S&P 1500 Value Index return of 42.51%, although the path to that performance for each was quite different. The more cyclically oriented value index had accumulated a 40% return in approximately the first seven months of the period as cyclical and reopening stocks were in favor. The growth index then took over leadership, outperforming the value index by approximately 20% over the last five months of the annual period. Rotations and changes in market leadership are typically thought of as healthy indicators of a rising market.

Within the S&P 1500 Growth Index, the smaller energy sector (less than 0.5% of the index on average over the course of the annual period) was the market leader with a 126% gain. Financials, also a smaller part of the growth market, gained 60% with communication services (+53%) and information technology (+51%) also outpacing the overall benchmark return. Industrials (+42%), consumer discretionary (+39%), real estate (+36%), health care (+35%), materials (+34%), utilities (+20%) and consumer staples (+19%) all lagged the benchmark's performance.

Calamos Growth Fund

Information technology holdings were the Fund's top contributor. While owing mostly to superior security selection, the Fund's overweight position added value as well. Semiconductors and semiconductor equipment names were the strongest outperforming industries. In addition, the Fund benefitted from a slight overweight as well as superior stock selection within the strong-performing financials sector. The portfolio increased its investment during the period to participate in strong cyclical growth opportunities and saw significant performance from investment banking & brokerage and consumer finance holdings.

Holdings in the communication services sector slightly lagged those of the market and detracted from the Fund's relative performance for the period. Fund names within interactive media and services as well as the movies and entertainment industries underperformed those of the market. Investments in the energy sector were also a slight detractor to relative performance, as names within oil & gas equipment & services lagged those of the overall market.

How is the Fund positioned?

The portfolio remains broadly diversified with a focus on a mix of durable, secular themes as well as more cyclical growth opportunities. We believe long-term secular growth stocks with strong balance sheets and dominant market positions will thrive in this environment. At the same time, cyclical growth companies that are more exposed to the ongoing global reopening should also do well. During the annual period, the Fund increased its investment in financials, shifting from an underweight to an overweight early in the period. We also added some higher-growth opportunities in communication services. The biggest decrease in relative positioning occurred in the consumer discretionary sector. The portfolio remains overweight as of period end, but the relative weight was reduced largely around names with higher valuations.

What closing thoughts do you have for Fund shareholders?

After a strong run of performance since the pandemic lows in early 2020, the backdrop for equities has become decidedly more complicated, but the longer-term underpinnings of the US economy and corporate profitability remain strong enough to support further gains. The most recent US GDP growth measure was notably disappointing, but we believe that this soft patch can be attributed to the midsummer delta-induced spike in Covid cases. As Covid cases have come down and vaccinations have scaled up globally, we have seen a return to stronger growth. US consumers remain in good financial standing with healthy household balance sheets and plentiful job opportunities. As a result, we anticipate at least another year or two of above-trend growth. Attention will deservedly be on Federal Reserve policy and the Fed's tapering of bond purchases, as well as the potential for changes in Fed Board membership. Moreover, questions around whether inflation and supply-chain issues are transitory or more entrenched will weigh on investors' minds going forward. Markets always present challenges, and sometimes they seem to come all at once. Nevertheless, above-trend economic growth, low interest rates, healthy consumer balance sheets, and a resilient and productive corporate sector continue to form a constructive backdrop for US equity markets.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Growth Fund

ANNUALIZED RETURN: SINCE INCEPTION (9/18/97) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Growth Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.35%, Class C shares is 2.11% and Class I shares is 1.10%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

† Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The S&P 1500 Growth Index consists of the growth segment of the securities found in the S&P 1500 Index. The S&P 1500 combines the S&P 500, S&P MidCap 400 and the S&P SmallCap 600.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Growth and Income Fund

OVERVIEW

The Fund invests primarily in US equity and convertible securities in an attempt to balance risk/reward while providing growth and income.

KEY FEATURES

^◼  Leverages more than four decades of research experience combining equities and convertible holdings to provide equity-like participation.

^◼  Provides a core holding option that aims to maintain a consistent risk posture throughout the market cycle.

^◼  Research-driven approach identifies opportunities by combining top-down analysis with a focus on key growth characteristics.

PORTFOLIO FIT

The Fund can provide a long-term core equity allocation, which exhibits potentially lower volatility and delivers attractive income.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS GROWTH AND INCOME FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Growth and Income Fund posted strong returns with a gain of 37.02% (Class I Shares at net asset value). Comparatively, the S&P 500 Index returned 42.91% for the period and the ICE BofA All US Convertibles ex Mandatory Index registered a gain of 34.01% for the period. We manage this Fund with the goal of achieving upside equity participation and potential downside risk mitigation over full market cycles. For the annual period, the Growth and Income Fund captured 86% of the all-equity index's returns. Since its Class I shares inception on September 18, 1997, the Fund returned 10.56% on an annualized basis versus an 8.80% gain for the S&P 500 Index and 9.49% return for the ICE BofA All US Convertibles ex Mandatory Index.

Please discuss the Fund's lower-volatility characteristics.

We believe the Fund's historical lower-volatility characteristics are a by-product of our investment style and focus on participating in equity market upside with less volatility than the market as a whole. Beta is one popular statistic for measuring volatility. Beta considers a fund's historic volatility versus the market, which is assigned a beta of 1.0. A fund with half the volatility of the market would have a beta of 0.5, while a fund with a beta of 2.0 would have been twice as volatile as the market. Since its inception, the Fund has had a beta of 0.75 (Class I shares) versus the S&P 500 Index. The Fund, therefore, outperformed the broader equity market, as measured by the S&P 500 Index, with less volatility than the equity market. Please note that past performance does not indicate future results and that beta is one of many measures of risk.

What factors influenced performance during the annual period?

As indicated by the performance figures, the US equity markets and risk markets in general enjoyed a very strong annual period. Companies reaped record corporate earnings as businesses benefited from a reopening economy, stimulative policy and strong consumer spending. Markets started the period with a strong move upward, as investor enthusiasm was buoyed by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets favored reopening trades, recognizing businesses that had the opportunity to rebound most from the negative impacts of the economic and social shutdowns, notably in travel, leisure, and restaurants as well as the energy and financials sectors more broadly. Near the middle of the annual period, secular growth businesses caught favor as investors turned their attention to businesses that might be able to generate high and sustainable growth without relying on a reopening economy.

The Fund benefitted from owning a mix of cyclical and secular growth businesses as market leadership rotated abruptly. All told, cyclically oriented names generally outperformed in various waves over the beginning of the annual period, whereas more secular growth names outperformed at points during the second half of the period. As an example, for the annual period, growth stocks and value stocks had similar

Calamos Growth and Income Fund

returns, as the S&P 500 Growth Index returned of 45.07% compared with the S&P 500 Value Index return of 41.01%, but the path to that performance was quite different between the two styles. The more cyclically oriented value index had accumulated a 37% return during the first seven months of the period as cyclical and reopening stocks were in favor, while the growth index was up "only" 23% during that time. The growth index then took over leadership, outperforming the value index by 15% during the last five months of the annual period. Rotations and changes in market leadership are typically thought of as healthy indicators for a rising market.

Looking at the all-equity market, within the S&P 500 Index, the smaller energy sector (less than 3% of the index on average over the course of the annual period) led the market with a 112% gain. Financials at 73%, information technology at 47%, and real estate at 46% also all outperformed the benchmark. Communication services (+42%), industrials (+40%), materials (+37%), consumer discretionary (+37%), health care (+34%), consumer staples (+19%), and utilities (+11%) each lagged behind the benchmark's performance.

For the annual period, the Fund was able to deliver significant equity market participation, even while utilizing convertible securities and options to reduce overall equity risk. The biggest benefactor to the Fund's relative performance was the consumer staples sector. Strong issue selection generated better performance than that of the all-equity S&P 500 Index, and the Fund's underweight to a more defensive area of the market was also additive. Specifically, strong issue selection in the materials sector was additive to relative performance, with notable contributions from copper and industrial gases. In industrials, select convertible securities offered good performance—and better risk management in our view—but did not keep pace with outright equity performance for the sector. Information technology is another sector in which the Fund had strong performance but lagged behind the all-equity S&P 500 Index sector constituents. The use of convertible securities offered attractive access to areas such as application software and data processing, but returns lagged behind those of the common stocks.

How is the Fund positioned?

From an asset class perspective, our positioning continues to favor equities over fixed income, with convertible securities being the most favored fixed-income security. With a decline in equity volatility over the last six months, we favor option strategies to manage risk, including creating synthetic convertibles with call options and buying put options for downside mitigation.

What closing thoughts do you have for Fund shareholders?

The transition from the recovery period of the Covid-induced economic cycle to the mid-cycle continues, as we discussed in our mid-year outlook. However, the transition has been volatile and will take longer than we originally thought. The demand side of the economy is still positive, as consumer and corporate spending should remain at above-trend levels as the Covid crisis abates; demand levels for services improve; and companies rebuild inventories, expand capacity, and improve productivity.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Growth and Income Fund

This change in the economic cycle and growth drivers should result in positive equity returns over the next 12 to 18 months but at more muted levels than the prior annual period. This investment regime change in the short term should indicate market leadership transitioning away from higher-risk equities (in both cyclical and growth areas) toward companies with higher return on capital, improved margins and less-volatile earnings. Third- and fourth-quarter 2021 earnings will highlight the severity of many of the issues described above, and the equity market may be volatile during this time. Once the market gets past these near-term issues, we expect better progress toward a more normalized environment in 2022.

ANNUALIZED RETURN: SINCE INCEPTION (9/18/97) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A, Class C and Class R6 shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Growth and Income Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.08%, Class C shares is 1.84%, Class I shares is 0.83% and Class R6 shares is 0.75%. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

The ICE BofA All US Convertibles EX Mandatory Index represents the US convertibles securities market excluding mandatory convertibles.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Dividend Growth Fund

OVERVIEW

The Fund invests in companies that we believe have the ability to increase dividends over time, either through increasing profits or more efficient use of capital.

KEY FEATURES

^◼  Employs bottom-up stock picking and a benchmark-agnostic approach.

^◼  Focuses on good businesses with solid cash flows and value prices.

PORTFOLIO FIT

The Fund may be suitable for investors seeking a regular stream of income and dividend-paying equity investments that tend to be less volatile than non-dividend payers.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS DIVIDEND GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Dividend Growth Fund returned 42.73% (Class I shares at net asset value), in line with the S&P 500 Index return of 42.91%.

What factors influenced performance during the annual period?

As indicated by the performance figures, the US equity markets and risk markets in general enjoyed a very strong annual period. Companies enjoyed record corporate earnings as businesses benefited from a reopening economy, stimulative policy and strong consumer spending. Markets started the period with a strong move upward, as investor enthusiasm was buoyed by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets favored reopening trades, recognizing businesses that had the opportunity to rebound most from the negative impacts of the economic and social shutdowns, notably in travel, leisure, and restaurants as well as the energy and financials sectors more broadly. Near the middle of the annual period, secular growth businesses caught favor as investors turned their attention back to businesses that might be able to generate high and sustainable growth without relying on a reopening economy.

The Fund benefitted from owning a mix of larger cap stocks among cyclical and secular growth businesses, as market leadership rotated abruptly. All told, cyclically oriented names generally outperformed in various waves over the beginning of the annual period, whereas more secular growth names outperformed at points during the second half of the period. As an example, for the annual period, growth stocks and value stocks had similar returns, as the S&P 500 Growth Index returned 45.07% compared with the S&P 500 Value Index return of 41.01%, but the path to that performance was quite different between the two styles. The more cyclically oriented value index had accumulated a 37% return during the first seven months of the period as cyclical and reopening stocks were in favor, whereas the growth index was up "only" 23% during that time. The growth index then took over leadership, outperforming the value index by 15% during the last five months of the annual period. Rotations and changes in market leadership are typically thought of as healthy indicators of a rising market.

Within the S&P 500 Index, the smaller energy sector (less than 3% of the index on average over the course of the annual period) led the market with a 112% gain. Financials (+73%), information technology (+47%), and real estate (+46%) also all outperformed the benchmark. Communication services (+42%), industrials (+40%), materials (+37%), consumer discretionary (+37%), health care (+34%), consumer staples (+19%), and utilities (+11%) each lagged behind the benchmark's performance.

The Fund benefitted from strong stock selection as well as an overweight to the strongly performing financials sector. Although financials was the second-leading sector within the benchmark, the Fund's selection significantly outperformed the sector overall. Fund investments in banking & brokerage and diversified banks were especially

Calamos Dividend Growth Fund

additive to performance. The Fund began the annual period with a slight underweight to financials and saw the relative weight increase slightly through a combination of purchases and strong performance. Strong selection within communication services also added to relative results for the period. Our efforts to be selective within integrated telecommunication services and interactive home entertainment added significant relative performance.

Health care names detracted value from the portfolio, predominantly because of underperformance among the health care equipment holdings. The Fund was underweight health care on average over the course of the year, which was modestly additive to relative performance. Real estate holdings also detracted from performance, as the portfolio was underweight the strongly performing residential REITs and retail REITs at the start of the period because we were seeking cyclical growth opportunities in other sectors.

How is the Fund positioned?

The Fund is broadly diversified by sector, favoring individual stock selection versus significant sector over and underweights. The Fund had started the annual period underweight energy, but over the course of the year, we increased the allocation and held a modest overweight at the end of the period. Similarly, the Fund added to health care stocks and ended the period with a slight overweight. The portfolio saw reductions in its industrials holdings as well as communication services names. The Fund's mix of common stocks combines cyclical and secular growth opportunities, though a focus on higher-quality and consistent earnings is anticipated as the economic backdrop changes.

What closing thoughts do you have for Fund shareholders?

The transition from the recovery period of the Covid-induced economic cycle to the mid-cycle continues, as we discussed in our mid-year outlook. However, the transition has been volatile and will take longer than we originally anticipated. The demand side of the economy is still positive, and consumer and corporate spending should remain at above-trend levels as the Covid crisis abates; demand levels for services improve; and companies rebuild inventories, expand capacity, and improve productivity.

This change in the economic cycle and growth drivers should result in positive equity returns over the next 12 to 18 months but at more muted levels than the prior annual period. This investment regime change in the short term should indicate market leadership transitioning away from higher-risk equities (in both cyclical and growth areas) toward companies with higher return on capital, improved margins and less-volatile earnings. Third- and fourth-quarter 2021 earnings will highlight the severity of many of the issues described above, and the equity market may be volatile during this time. Once the market gets past these near-term issues, we expect better progress toward a more normalized environment in 2022.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Dividend Growth Fund

GROWTH OF $1,000,000: SINCE INCEPTION (8/05/13) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 2.16%, Class C shares is 2.92% and Class I shares is 1.89%. The Fund's Investment Adviser has contractually agreed to reimburse Fund expenses through 3/1/23 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses and extraordinary expenses, if any) of Class A, Class C and Class I shares are limited to 1.35%, 2.10%,1.10% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum frontend sales load of 4.75% for Class A shares. Returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graph does not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Select Fund

CALAMOS SELECT FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Select Fund returned 44.28% (Class I shares at net asset value), outperforming the S&P 500 Index return of 42.91%.

What factors influenced performance during the annual period?

As indicated by the performance figures, the US equity markets and risk markets in general enjoyed a very strong annual period. Companies reaped record corporate earnings as businesses benefited from a reopening economy, stimulative policy and strong consumer spending. Markets started the period with a strong move upward, as investor enthusiasm was buoyed by positive data on Covid vaccine efficacy and the prospect of vaccines rolling out in early 2021. Initially, markets favored reopening trades, recognizing businesses that had the opportunity to rebound most from the negative impacts of the economic and social shutdowns, notably in travel, leisure, and restaurants as well as the energy and financials sectors more broadly. Near the middle of the period, secular growth businesses caught favor as investors turned their attention back to businesses that might be able to generate high and sustainable growth without relying on a reopening economy.

The Fund benefitted by increasing its allocation to cyclical growth names earlier in the annual period, and then shifting more investment toward secular growth later in the period. For the annual period, growth stocks and value stocks had similar returns, as the S&P 500 Growth Index returned of 45.07% compared with the S&P 500 Value Index return of 41.01%, but the path to that performance was quite different between the two styles. The more cyclically oriented value index had accumulated a 37% return during the first seven months of the annual period as cyclical and reopening stocks were in favor, whereas the growth index was up "only" 23% during that time. The growth index then took over leadership, outperforming the value index by 15% during the last five months of the annual period. Rotations and changes in market leadership are typically thought of as healthy indicators of a rising market.

Within the S&P 500 Index, the smaller energy sector (less than 3% of the index on average over the course of the reporting period) led the market with a 112% gain. Financials (+73%), information technology (+47%), and real estate at (+46%) also all outperformed the benchmark. Communication services (+42%), industrials (+40%), materials (+37%), consumer discretionary (+37%), health care (+34%), consumer staples (+19%), and utilities (+11%) each lagged the benchmark's performance.

On the whole, stock selection was additive to relative performance over the course of the annual period, as the Fund outperformed the S&P 500 Index. Sector allocations for the Fund were a detractor largely due to an underweight to the small, yet strong performing energy sector.

Specifically, the Fund benefitted from strong stock selection within the financials sector as well as an overweight to the strongly performing sector. Although financials was the second leading sector within the benchmark, Fund selections significantly

OVERVIEW

The Fund primarily invests in a concentrated portfolio of large-cap US equities with broad representation across sectors and industries. In addition, the Fund can invest across investment styles in the US equity market.

KEY FEATURES

ⁿ  Security selection is based mainly on Calamos analysts' highest conviction ideas. We leverage the collective expertise of the firm's research analysts, who average 15+ years of experience in their areas of expertise.

ⁿ  The investment process is driven by rigorous fundamental and sector-specific research. The goal is to maximize exposure to opportunities the team believes are compelling.

ⁿ  Quantitative tools help minimize systematic risks across both sectors and factors. We use quantitative tools to minimize unintended bets and maximize the impact of security selection.

PORTFOLIO FIT

Because the Fund pairs a high-conviction approach with a broad investment universe, we believe it is an attractive choice for investors seeking a long-term core equity allocation to US stocks.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Select Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

outperformed those of the benchmark sector overall. Fund holdings in three industries—investment banking & brokerage, diversified banks, and consumer finance—were additive to performance. The Fund began the period with a slight overweight to financials and saw the relative weight increase slightly through purchases as well as strong performance. Strong selection within health care also added to relative performance for the annual period, as pharmaceuticals and health care equipment selections notably outperformed.

Consumer discretionary names detracted value from the portfolio, predominantly because of underperformance among internet & direct retail holdings. Real estate holdings also detracted from performance, as the portfolio was underweight the sector at the start of the period and exited the sector entirely in favor of opportunities elsewhere.

How is the Fund positioned?

The portfolio remains broadly diversified with a focus on a mix of durable, secular themes as well as more cyclical growth opportunities. At the end of the annual period, the Fund held 61 names. During the period, the Fund increased its relative weights to the consumer staples and communication services sectors. Within consumer staples, new names were added to the portfolio within foods distributors and packaged foods & meats. Consumer discretionary names were added in autos, auto parts, and casinos & gaming. Conversely, relative Fund weightings were reduced in information technology and the previously mentioned real estate sector. The Fund is broadly diversified by sector, favoring individual stock selection to significant sector over and underweights.

What closing thoughts do you have for Fund shareholders?

After a strong run of performance since the pandemic lows in early 2020, the backdrop for equities has become decidedly more complicated, but the longer-term underpinnings of the US economy and corporate profitability remain strong enough to support further gains. The most recent US GDP growth measure was notably disappointing, but we believe that this soft patch can be attributed to the midsummer delta-induced spike in Covid cases. As Covid cases have come down and vaccinations have scaled up globally, we have seen a return to stronger growth. US consumers remain in good financial standing with healthy household balance sheets and plentiful job opportunities. As a result, we anticipate at least another year or two of above-trend growth. Attention will deservedly be on Federal Reserve policy and the Fed's tapering of bond purchases, as well as the potential for changes in Fed Board membership. Moreover, questions around whether inflation and supply-chains issues are transitory or more permanent will weigh on investors' minds going forward. Markets always present challenges, and sometimes they seem to come all at once. Nevertheless, above-trend economic growth, low interest rates, healthy consumer balance sheets, and a resilient and productive corporate sector continue to form a constructive backdrop for US equity markets.

Calamos Select Fund

ANNUALIZED RETURN: SINCE INCEPTION (3/1/02) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Performance shown reflects an expense reimbursement that improved results. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Select Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.64%, Class C shares is 2.40% and Class I shares is 1.39%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023, to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.15%, 1.90%, and 0.90% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The S&P 500 Index is an unmanaged index generally considered representative of the US stock market.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos International Growth Fund

CALAMOS INTERNATIONAL GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos International Growth Fund returned 33.13% (Class I shares at net asset value) versus a 30.38% gain for the MSCI EAFE Growth Index. The Fund's one-year return was in the top 20th percentile of the Morningstar Foreign Large Growth category*, reflecting the benefit of our active investment approach. The Fund navigated highly rotational markets during the Covid recovery phase and captured leading returns in international stocks over the period.

Since its inception on March 17, 2005, the Fund has returned 9.46% on an annualized basis (Class I shares at net asset value) compared with a 7.41% return for the MSCI EAFE Growth Index. We believe this long-term record demonstrates the Fund's ability to generate excess returns in international growth equities over complete market cycles.

What factors influenced performance during the reporting period?

International equities advanced over the annual period as markets reflected the economic recovery and Covid vaccination progress, while also confronting the impact of supply chain disruptions and rising inflation. The Fund generated strong returns over the annual period due to a combination of favorable top-down positioning and relative security selection.

Fund positioning benefited from a relative overweight in developed markets, including Europe, and a blend of secular growth and more cyclical opportunities. From a bottom-up perspective, many of the Fund's holdings in companies with advantaged business models, effective pricing power and growing market share performed well over the annual period.

The Fund's average overweight position and leading security selection in information technology positively contributed to relative performance. Our holdings in semiconductor equipment and application software notably propelled relative returns. Favorable security selection and an average overweight position in financials also added to the Fund's performance, especially in the diversified banks and regional banks industries.

Over the annual period, selection within the consumer discretionary sector held back relative results, as holdings in the internet & direct marketing retail industry and apparel, accessories & luxury goods industry curbed return. Security selection and an average underweight position in industrials, specifically in the trading companies & distributors and building products industries, also hurt relative results.

OVERVIEW

The Fund offers a dynamic approach to accessing international growth opportunities. We apply our active investment approach to build a portfolio of companies with superior growth and quality attributes across developed and emerging market.

KEY FEATURES

ⁿ  Identifies companies with compelling growth, competitive advantages and financial strength.

ⁿ  Identifies durable secular themes that provide a tailwind for sustainable growth and a franchise premium.

ⁿ  Investment universe spans geographies and market caps, providing a wide breadth of opportunities.

ⁿ  Takes environmental, social and governance (ESG) factors into account, evaluating the effects on a company's risk profile, cash flow and long-term returns.

PORTFOLIO FIT

As an active, true growth offering with a differentiated return profile, the Fund can potentially help investors optimize capital appreciation within their international allocation.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

*  Data is as of 10/31/21. Morningstar category percentile ranking is based on annualized total return for the 1-year, 3-year, 5-year and 10-year periods. In the Morningstar Foreign Large Growth category, Calamos International Growth Fund Class I shares were in the 20th, 11th, 13th and 37th percentiles of 447, 385, 326 and 223 funds for the 1-year, 3-year, 5-year and 10-year periods, respectively.

Calamos International Growth Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

From a regional standpoint, the Fund's overweight allocation and security selection in the United States aided results. Similarly, an underweight stance and security selection in Japan added value to Fund performance.

Conversely, an overweight allocation in Emerging Asia lagged on a relative basis. Specifically, positions in China and South Korea held back relative performance. Moreover, an overweight stance and selection in Emerging Latin America dampened results. In particular, our holdings in Brazil and Argentina represented detractors.

How is the Fund positioned?

The Fund's regional and country positioning reflects the combined inputs from our top-down global framework and our bottom-up security analysis. Our investment team evaluates macroeconomic factors and growth opportunities and actively integrates these into the investment decision-making process.

We have positioned the portfolio with a combination of secular-growth companies and increased cyclical opportunities whose economically sensitive businesses are positioned to benefit from more synchronized global growth in the quarters ahead.

Technology, consumer discretionary, industrials and financials are the largest sector weights in the Fund. We hold key industry positions in semiconductors, diversified banks, apparel & luxury goods, industrial machinery, and health care supplies. We have an underweight stance in more defensive areas including utilities, real estate, consumer staples and more traditional telecoms.

From a geographic perspective, we own diversified holdings in Europe, investing in a blend of end markets and business types. Positioning is largely in global secular demand areas and in cyclical opportunities leveraged to the next stages of the economic recovery and expansion. In Japan, we hold a set of higher-quality companies with leading business models that are positioned to benefit from rising global demand as the recovery broadens in the months ahead. Within emerging markets, we also hold a blend of secular growth and more cyclical businesses that are well positioned to take advantage of reopening opportunities. We own positions in key demand areas such as semiconductors, interactive media & services, branded apparel, life sciences tools, and higher-quality financials.

What closing thoughts do you have for Fund shareholders?

International stocks continue to navigate a range of shifting crosscurrents. We are analyzing the global economic recovery, alongside policy actions and the path of corporate earnings. Global monetary policy remains supportive overall, though multiple central banks have edged toward a less-accommodative stance. We see many opportunities in international markets, reflective of strong earnings, reasonable valuations, and substantial progress in vaccinations. Despite these potential tailwinds, we are mindful that markets will experience volatility and we remain closely attuned to risks.

From a thematic and sector perspective, we see opportunities in technology, consumer discretionary, industrials, health care and financials with competitive advantages that target critical demand areas. Our active investment approach and long-term perspective positions us to take advantage of opportunities in foreign markets.

Calamos International Growth Fund

ANNUALIZED RETURN: SINCE INCEPTION (3/16/05) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A, Class C and Class R6 shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos International Growth Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.52%, Class C shares is 2.27%, Class I shares is 1.28% and Class R6 shares is 1.17%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.10%, 1.85%, and 0.85% of average net assets, respectively. The Fund's investment adviser has contractually agreed to limit the Fund's annual ordinary operating expenses for Class R6 shares (as a percentage of average net assets) to 0.85% less the annual sub-transfer agency ratio for the Fund. The annual sub-transfer agency ratio is equal to the aggregate sub-transfer agency expenses common to the other share classes of the Fund divided by the aggregate average annual net assets of the Fund's other share classes. For purposes of these expense limitations, operating expenses do not include taxes, interest, short interest, short dividend expenses, all commissions and other normal charges incident to the purchase and sale of portfolio securities, and extraordinary expenses, if any. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The MSCI EAFE Growth Index measures developed market growth equity performance (excluding the US and Canada).

The MSCI ACWI ex US Index represents the performance of large- and mid-cap stocks across developed and emerging markets excluding the United States. The MSCI ACWI ex US Index is provided to show how the Fund's performance compares with the returns of an index of securities similar to those in which the Fund invests.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Evolving World Growth Fund

CALAMOS EVOLVING WORLD GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the annual period ended October 31, 2021, Calamos Evolving World Growth Fund returned 16.17% (Class I shares at net asset value), capturing most of the upside in emerging markets versus the 17.33% return for the MSCI Emerging Market Index. The Fund's returns over the extended pandemic cycle reflected the benefit of our risk-managed investment approach, which was instrumental in dampening volatility and navigating through highly rotational global markets.

Since its inception on August 15, 2008, the Fund has returned 7.16% on an annualized basis (Class I shares at net asset value) compared with a 4.26% return for the MSCI Emerging Markets Index. We believe this demonstrates the Fund's ability to generate competitive long-term returns while pursuing an active, risk-managed approach to emerging markets over multiple market cycles.

What factors influenced performance during the annual period?

Emerging markets saw a choppy return environment over the annual period, reflecting mixed progress in economic recoveries and Covid vaccination numbers across regions, while also navigating the impact of supply-chain disruptions and rising inflation. The Fund's attractive total return over the annual period was attributable to active risk management tactics, including holdings in convertible bonds, which contributed to a favorable risk/reward profile and strong upside capture over the period. In addition, the Fund return benefited from favorable bottom-up security selection and top-down positioning across sectors. Many of the Fund's holdings in companies with advantaged business models and secular demand tailwinds performed well amid a volatile and highly rotational market environment.

From a sector perspective, the Fund added value in terms of sector positioning and security selection. The Fund's security selection in technology and communication services added value over the annual period due to a combination of resilient business models and better growth prospects. Specifically, names in semiconductors and semiconductor equipment were sources of strength in information technology, and holdings in the interactive home entertainment and movies & entertainment industries especially helped in communication services.

Over the annual period, an average underweight position and selection within the energy sector detracted from relative results, as holdings in the oil & gas refining & marketing and integrated oil & gas industries underperformed. Security selection in financials, specifically in the diversified banks and investment banking & brokerage industries, also lagged on a relative basis.

OVERVIEW

The Fund offers an active, risk-managed strategy to access growth opportunities in emerging markets. The Fund invests in emerging market-domiciled and developed market-domiciled companies with significant revenue exposures attributable to emerging markets.

KEY FEATURES

ⁿ  Focuses on higher-quality companies with compelling growth attributes.

ⁿ  Conducts research across the capital structure and utilizes Calamos' experience in convertible securities to dynamically manage the risk profile.

ⁿ  Emphasizes countries enacting structural reforms and improving economic freedoms, which we believe enhances growth prospects and mitigates risk.

ⁿ  Identifies durable secular themes that provide a tailwind for sustainable growth and a franchise premium.

PORTFOLIO FIT

Because of its focus on risk management, the fund can serve as a long-term emerging-market allocation.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Evolving World Growth Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

In terms of geographic returns, the Fund's relative overweight in India and underweight in China over the annual period added value. The Fund's security selection within Taiwan and Mexico also contributed to returns, while the Fund's holdings in Korea and Russia trailed the index return.

How is the Fund positioned?

We maintain a constructive view on opportunities in emerging markets. Our Fund positioning favors a blend of secular growth and more cyclical businesses, with increased opportunities in reopening beneficiaries. From a sector perspective, the largest weights are in financials, consumer discretionary, technology and communication services. We own holdings within key demand areas including semiconductors, higher-quality financials, interactive media & services, branded apparel, and internet retail. We hold a low weight or underweight in the consumer staples and utilities sectors, reflecting our view of more attractive opportunities in the sectors noted above.

At the individual company level, we favor businesses with growth catalysts, attractive capital efficiency and stronger balance sheets that are supported by solid competitive positioning. In line with our process, we emphasize companies benefiting from secular themes that provide a tailwind for sustainable growth into the future. From a geographic perspective, we favor investments in markets including India, Taiwan, Mexico, select names in China, and increased opportunities in Southeast Asia.

What closing thoughts do you have for Fund shareholders?

Emerging markets continue to navigate a range of crosscurrents and highly disparate conditions depending on the region. We are analyzing many aspects of economic activity, alongside key policy actions and corporate earnings. Global monetary policy remains supportive overall, while multiple central banks have edged toward a less-accommodative stance. We see opportunities in emerging markets, reflecting our view of a more synchronized recovery ahead due to increasing vaccination numbers and improving supply-chain dynamics. Despite these potential tailwinds, we are mindful that markets will experience volatility, and we remain closely attuned to risks.

We own a blend of investments in secular growth companies, more cyclical opportunities leveraged to the global economy and select reopening businesses. We favor investments in companies with advantaged business models, flexible balance sheets, and the ability to compound growth over the medium to long term. From a thematic and sector perspective, we see opportunities in consumer discretionary, communications services, higher quality financials, technology and cyclicals with competitive advantages that target in-demand areas. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in emerging markets.

Calamos Evolving World Growth Fund

ANNUALIZED RETURN: SINCE INCEPTION (8/15/08) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their?original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Evolving World Growth Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.64%, Class C shares is 2.39% and Class I shares is 1.39%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.30%, 2.05%, and 1.05% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graph does not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The MSCI Emerging Markets Index is a free float-adjusted market capitalization index considered broadly representative of emerging market equity performance. The index represents companies within the constituent emerging markets that are available to investors worldwide. The index is calculated on a total return basis, which includes reinvestment of gross dividends before deduction of withholding taxes.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

The Fund's use of derivative instruments involves investment risks and transaction costs to which the Fund would not be subject absent the use of these instruments and, accordingly, may result in losses greater than if they had not been used. Derivative instruments can be illiquid, may disproportionately increase losses and may have a potentially large impact on Fund performance.

Calamos Global Equity Fund

CALAMOS GLOBAL EQUITY

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Global Equity Fund returned 40.29% (Class I shares at net asset value) versus a 41.05% gain for the MSCI World Index and a 37.86% return for the MSCI ACWI Index. The Fund's one-year return was in the top 15th percentile of the Morningstar World Large Stock Growth category*. The return reflected the benefit of our active investment approach, which was instrumental in adapting to highly rotational markets through the Covid market recovery and capturing the upside in global stocks over the annual period.

Since its inception on March 2, 2007, the Fund has returned 10.78% on an annualized basis (Class I shares at net asset value) compared with an 8.01% increase in the MSCI World Index and 7.64% return in the MSCI ACWI Index. We believe this demonstrates the Fund's ability to generate long-term excess returns over complete market cycles and varied investment environments.

What factors influenced performance during the annual period?

Global stocks advanced over the annual period as markets reflected the economic recovery and Covid vaccination progress, while also confronting the impact of supply-chain disruptions and rising inflation. The Fund generated strong returns over the annual period due to a combination of leading security selection and favorable sector positioning. Many of the Fund's holdings in global companies with advantaged business models performed well, and the Fund's positioning benefited from a blend of secular growth and more cyclical opportunities.

From a sector perspective, the Fund's security selection and an average overweight position in information technology helped drive relative returns. Specifically, semiconductors and semiconductor equipment bolstered relative results. An average underweight allocation in consumer staples also contributed to performance. Notably, soft drinks and our lack of representation in household products promoted return.

Over the annual period, security selection and an average overweight stance within the consumer discretionary sector dampened return, as holdings in the internet & direct marketing retail and automobile manufacturers industries hurt relative performance. Selection within the oil & gas, refining & marketing and integrated oil & gas industries of the energy sector also lagged.

From a geographic standpoint, the Fund's security selection in the United States drove relative results. Favorable security selection in Europe also added value to Fund performance. Specifically, holdings in the Netherlands and Luxembourg were leading contributors.

Conversely, the Fund's overweight allocation in Emerging Asia dragged on return. Particularly, holdings in China and Australia hindered return. In addition, security selection and an underweight stance in Canada weakened relative performance.

OVERVIEW

The Fund invests in equities of companies around the globe. We seek firms demonstrating what we believe to be key growth characteristics, including increasing profit margins and high returns on invested capital.

KEY FEATURES

ⁿ  Flexibly seeks growth globally, searching for the best risk/reward opportunities across countries, market capitalizations and sectors.

ⁿ  Seeks global growth companies that may benefit from long-term secular themes, including a burgeoning global middle class and increasing demand for information and entertainment.

PORTFOLIO FIT

The Fund can serve as a growth-oriented addition to a strategic global equity allocation and may complement or provide an alternative to value or blended styles.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

*  Data is as of 10/31/21. Morningstar category percentile ranking is based on annualized total return for the 1-year, 3-year, 5-year and 10-year periods. For the Morningstar World Large-Stock category, Calamos Global Equity Fund Class I shares were in the 15th, 24th, 31st and 58th percentiles of 354, 307, 262 and 166 funds for the 1-year, 3-year, 5-year and 10-year periods, respectively.

Calamos Global Equity Fund

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

How is the Fund positioned?

The Fund's regional and country positioning reflects the combined inputs from our top-down global framework and our bottom-up security analysis. Our investment team evaluates macroeconomic factors and growth opportunities, and actively integrates them into the investment decision-making process. We have positioned the Fund with a combination of secular growth leaders and increased cyclical exposures in more economically sensitive and reopening opportunities. Technology, consumer discretionary, financials, health care and communication services are the largest sector weights in the Fund. We hold key industry positions in semiconductors, diversified banks, internet retail, interactive media & services, systems software, and life sciences tools. We hold selective weight in materials and energy, with holdings in companies positioned to benefit from strong global demand and higher commodity prices. We are underweight to more defensive sectors including utilities, real estate, consumer staples and traditional telecoms, given the unattractive relative valuations and growth potential.

Through a geographic lens, we own a set of secular growth businesses and cyclical opportunities in the United States with its positive economic backdrop and wider set of opportunities. In Europe, we own a diversified set of holdings with a blend of end markets and business types. Positioning is largely in global secular demand areas and cyclical opportunities leveraged to a recovery. We have a relatively even-weight position in Japan. We own several high-quality companies with leading business models that are positioned to benefit from rising global demand. We own positions in emerging markets within key demand areas such as semiconductors, branded apparel, health care and higher-quality banks.

What closing thoughts do you have for Fund shareholders?

Global stocks continue to navigate a range of shifting crosscurrents. We are analyzing the global recovery and many aspects of economic activity, alongside policy actions and the path of corporate earnings. Global monetary policy remains supportive overall, while multiple central banks have edged toward a less-accommodative stance. We see many opportunities in global stocks, reflective of strong earnings and substantial progress in global vaccine rollouts and reopenings. Despite these potential tailwinds, we are mindful that markets will experience volatility, and we remain closely attuned to risks.

From a thematic and sector perspective, we see opportunities in technology, consumer discretionary, financials, and health care with competitive advantages that target critical demand areas. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in global markets.

Calamos Global Equity Fund

ANNUALIZED RETURN: SINCE INCEPTION (3/1/07) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A, Class C and Class R6 shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Global Equity Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.65%, Class C shares is 2.40%, Class I shares is 1.40% and Class R6 shares 1.34%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.40%, 2.15%, and 1.15% of average net assets, respectively. The Fund's investment advisor has contractually agreed to limit the Fund's annual ordinary operating expenses for Class R6 shares (as a percentage of average net assets) to 1.15% less the annual sub-transfer agency ratio for the Fund. The annual sub-transfer agency ratio is equal to the aggregate sub-transfer agency expenses common to the other share classes of the Fund divided by the aggregate average annual net assets of the Fund's other share classes. For purposes of this expense limitation, operating expenses do not include taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graph does not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

Calamos Global Equity Fund

The MSCI World Index (USD) is a free float-adjusted market-capitalization-weighted index composed of companies representative of the market structure of developed market countries in North America, Europe and the Asia/Pacific region.

The MSCI ACWI (USD) Index is a free float-adjusted market-capitalization-weighted index that is designed to measure the equity market performance of companies in developed and emerging markets. The MSCI ACWI (USD) Index is provided to show how the Fund's performance compares with the returns of an index of securities similar to those in which the Fund invests.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Global Opportunities Fund

OVERVIEW

The Fund invests primarily in global equity and convertible securities with an aim to balance risk/reward while providing growth and income.

KEY FEATURES

ⁿ  Combines equity and convertible holdings in order to limit downside risk while potentially capturing upside equity participation.

ⁿ  Provides a core holding option that strives to maintain a consistent risk posture throughout the market cycle.

ⁿ  Seeks to participate in the upside movements of the global equity market while lessening the impact of down periods.

PORTFOLIO FIT

The Fund can provide a long-term core allocation to global equities with the potential for lower volatility over full market cycles.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS GLOBAL OPPORTUNITIES FUND

(formerly Calamos Global Growth and Income Fund)

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), Calamos Global Opportunities Fund returned 35.16% (Class I shares at net asset value) versus a 37.86% gain for the MSCI ACWI Index. The Fund's one-year return was in the top 10th percentile of the Morningstar World Allocation category,* reflecting the benefit of our active risk-managed global approach, which was instrumental in navigating a significant market rotation and volatility during the Covid recovery phase of the global economy.

Since Class I shares inception on September 18, 1997, the Fund has returned 8.50% on an annualized basis (Class I shares at net asset value) compared with a 7.32% return for the MSCI ACWI Index. We believe this demonstrates the Fund's ability to generate attractive long-term returns while pursuing an active, risk-managed investment approach over complete market cycles.

What factors influenced performance during the annual period?

Global markets rose over the annual period, reflecting progress in the economic recovery and Covid vaccinations, while demonstrating resiliency in the face of supply-chain disruptions and rising inflation. The Fund's excellent risk-adjusted performance was attributable to the benefit of active risk management tactics, including holdings in convertible bonds that contributed to a favorable risk/reward profile and strong upside capture this year. In addition, the Fund benefited from favorable top-down positioning across regions and contributions from relative security selection. Many of the Fund's core holdings in global companies with advantaged business models and secular demand tailwinds performed well amid a volatile and highly rotational market environment.

The Fund's security selection and an average overweight position in information technology boosted relative performance. In particular, our holdings in semiconductor equipment and data processing & outsourced services were sources of strength. In addition, security selection in financials added to the Fund's performance. The main contributors within this sector were diversified banks and investment banking & brokerage.

Over the period, selection and an average overweight position within the consumer discretionary sector detracted from relative returns, as holdings in the internet & direct marketing retail and apparel, accessories & luxury goods industries lagged. Security selection in energy hurt relative results, especially in the oil & gas refining & marketing and integrated oil & gas industries.

*  Data is as of 10/31/21. Morningstar category percentile ranking is based on annualized total return for the 1-year, 3-year, 5-year and 10-year periods. For the Morningstar World Allocation category, Calamos Global Opportunities Fund Class I shares were in the 10th, 1st, 1st and 6th percentiles of 439, 401, 351 and 233 funds for the 1-year, 3-year, 5-year and 10-year periods, respectively.

Calamos Global Opportunities Fund

From a regional standpoint, security selection in Europe added value to fund performance. In particular, Fund holdings in the Netherlands and Denmark represented major contributors. Leading security selection and an overweight position in the United States also boosted fund performance.

Conversely, selection in Emerging Asia negatively impacted the Fund's performance. Specifically, holdings in India and China lagged the benchmark and detracted value. Similarly, security selection in EMEA dampened relative results. Positions in Israel hurt relative performance, and our lack of exposure to Russia held back return.

In terms of economic sectors, the largest allocations reside in information technology and consumer discretionary on an absolute basis, whereas the smallest sector weight allocations with holdings are found within utilities and real estate. On a relative basis, health care supplies and movies & entertainment constitute the most significant relative overweights.

Allocations to financials and information technology rose during the period with increased weights in diversified banks and systems software. By contrast, allocations to consumer discretionary and industrials decreased over the period with reductions to internet & direct marketing retail and airlines.

From a regional standpoint, the Fund's largest weights are in the United States and Europe. Conversely, EMEA and Emerging Latin America represent the smallest absolute weights. Allocations to the United States rose during the period. By contrast, the allocations to Emerging Asia decreased over the period with reductions to China and India.

From a sector perspective, the Fund's security selection in technology, financials, and health care added significant value, as holdings in the semiconductors, health care supplies, and diversified banks industries performed well over the annual period. The Fund's holdings in consumer discretionary, energy, and industrials trailed the index and held back returns over the period. From a geographic perspective, the Fund's holdings in Europe and the United States generated strong returns and added value to returns over the year, while fund holdings in Emerging Asia underperformed the index and hampered returns.

How is the Fund positioned?

The Fund's regional and country positioning reflects the combined inputs from our top-down global framework and our bottom-up security analysis. Our investment team evaluates macroeconomic factors and growth opportunities and actively integrates these into the investment decision-making process.

We positioned the Fund with a combination of secular growth leaders and increased cyclical exposure in more economically sensitive and reopening opportunities. Technology, consumer discretionary, communication services and financials comprise the largest sector weights in the Fund. We hold key industry positions in semiconductors, diversified banks, internet retail, interactive media & services, systems software and health care supplies. We own select positions within materials and energy, with holdings in companies positioned to benefit from strong global demand and elevated commodity prices. We are underweighted in more defensive sectors including utilities, real estate, consumer staples and traditional telecoms, reflecting our unfavorable view of relative growth potential and valuations in these sectors.

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos Global Opportunities Fund

From a geographic perspective, we own a set of secular growth businesses and cyclical opportunities in the United States with its positive economic backdrop and wider set of opportunities. In Europe, we own a diversified set of holdings with a blend of end markets and business types. Positioning is largely in global secular demand areas and in cyclical opportunities leveraged to a recovery. We have a relatively even-weight position in Japan. We own several high-quality companies with leading business models positioned to benefit from rising global demand and domestic stimulus measures. We own positions in emerging markets within key demand areas such as semiconductors, branded apparel, health care and higher-quality banks.

What closing thoughts do you have for Fund shareholders?

Global markets continue to navigate a range of shifting crosscurrents. We are analyzing the global recovery and many aspects of economic activity alongside policy actions and the path of corporate earnings. Global monetary policy remains supportive overall, while multiple central banks have edged toward a less-accommodative stance. We see many opportunities in global stocks and convertibles, reflective of strong earnings and substantial progress in global vaccinations and reopening. Despite these potential tailwinds, we are mindful that markets will experience volatility and we remain closely attuned to risks.

From a thematic and sector perspective, we see opportunities in technology, consumer discretionary, financials, and health care with competitive advantages that target critical demand areas. Our active, risk-managed investment approach and long-term perspective positions us to take advantage of volatility and opportunities in global markets.

Calamos Global Opportunities Fund

ANNUALIZED RETURN: SINCE INCEPTION (9/18/97) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Global Opportunities Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.53%, Class C shares is 2.28% and Class I shares is 1.28%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.22%, 1.97%, and 0.97% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 4.75% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The MSCI ACWI Index is a free float-adjusted market-capitalization-weighted index that is designed to measure the equity market performance of developed and emerging markets.

The MSCI World Index (US Dollars) is a market-capitalization-weighted index composed of companies representative of the market structure of developed market countries in North America, Europe and the Asia/Pacific region. Since inception data for the index is shown from 9/30/97 since data is only available for full monthly periods.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Total Return Bond Fund

CALAMOS TOTAL RETURN BOND FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), the Fund returned 0.17% (Class I shares at net asset value), outperforming the -0.48% return of the Bloomberg US Aggregate Bond Index.

Since Class I shares inception on June 27, 2001, the Fund gained 4.24% on an annualized basis versus a 4.20% return for the Bloomberg US Aggregate Bond Index.

What factors influenced performance?

Record corporate earnings, strong economic growth, a reopening economy, investor optimism and extraordinary fiscal and monetary stimulus provided an atmosphere supportive of strong performance across risk assets over the annual period. Equity markets across capitalizations and geographies delivered robust returns, while credit spreads in developed economies are trading near all-time tights, reflecting historically low default rates and continued economic expansion.

Covid lingers, and mutations of the virus continue to pose a threat. However, vaccination progress continues. Tens of millions of shots are being administered daily worldwide, and nearly 50% of the global population has now been fully vaccinated. Fiscal policy has always been an important consideration for investors, but the size and scope of Covid-related relief packages introduced over the annual period have been exceptional. While not specifically associated with Covid, further government spending packages, including the recently passed $1 trillion infrastructure bill, will inject massive sums into the domestic economy.

OVERVIEW

Through its multi-sector fixed-income strategy, the Fund invests predominantly in US issuers with the goal of generating a high level of both current income and total return in excess of the benchmark over full market cycles.

KEY FEATURES

ⁿ  Employs bond-by-bond portfolio construction with a focus on being well compensated for risks taken. We believe a disciplined process, grounded in fundamental research, enables us to achieve higher total returns with less volatility.

ⁿ  Draws on a broader investable universe to enhance portfolio construction and risk management. The inclusion of high-yield bonds, bank loans and preferreds provides additional opportunities.

ⁿ  Utilizes robust, independent credit research. Our fixed-income investment process unites quantitative and qualitative analyses into historical and forward-looking models. The result is a credit rating reflective of where a company is heading.

ⁿ  Applies a macro overlay to capitalize on misunderstood industries and sectors. The overlay acts as a risk control that also considers the business cycle, geopolitical factors, inflation and real-rate expectations.

PORTFOLIO FIT

The Fund may be suitable as the cornerstone of a fixed-income allocation, with investments diversified across the major sectors of the US bond market. Allocations to specialized fixed-income strategies seek to enhance return potential and better manage risk.

FUND NASDAQ SYMBOLS

Calamos Total Return Bond Fund

FUND CUSIP NUMBERS

ASSET ALLOCATION

Asset Allocation weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Over the course of the annual period, the Federal Reserve has also continued to provide a remarkable level of monetary stimulus by holding its overnight borrowing rate at 0.0% while purchasing over $1 trillion of Treasury and mortgage-backed securities to maintain easy financial conditions. Continued progress toward the Fed's goal of full employment is drawing us closer to a reduction of monetary stimulus, with the Fed expected to announce a taper of its asset purchases beginning in late 2021. Real interest rates, which measure the risk-free compensation an investor receives after inflation, have been negative since January 2020, providing support for risk assets. In 2010, real interest rates also crossed into negative territory, and remained there for 42 consecutive months, which helped fuel the longest economic expansion in post-WWII history. If real rates were to remain negative for a similar duration now, this scenario would extend into the middle of 2023. This consideration is one of the factors contributing to the market's optimism for continued above-trend expansion.

To be sure, challenges exist, and inflation is primary among them. Higher inflation eats into the financial benefit of economic growth, impacting the amount of real consumption by consumers. Headline inflation (inclusive of energy and food prices) is measuring above 5%, the highest rate in 30 years. Inflation related to wages and housing, which have historically been signals of stickier inflation, are also climbing higher indicating that inflation may not be as transitory as many hoped. One source of inflation has been ongoing supply-chain challenges stemming from the global economic shutdown that occurred at the onset of the Covid pandemic. The reopening of several industries has been stymied as component parts must be manufactured and delivered via congested ports and understaffed trucking companies. Despite these challenges, consumer demand, as measured by personal spending and GDP growth, is expanding at healthy levels, informing the market's expectations for continued strength.

During the first half of the annual period, investment-grade corporate-credit markets continued to enjoy a rapid recovery from the height of the pandemic, collapsing from more than 125 basis points over like-maturity Treasuries to inside of 90 basis points. A tight trading range has been established since April, with spreads fluctuating in a 10-basis-points range between 80 and 90 basis points. 2020 was a record year for issuance volume in the investment-grade market, and while 2021 volumes are tracking roughly 20% below 2020, this year is likely to close with the second-highest volume ever. The Bloomberg US Corporate Index closed the annual period with option adjusted spreads at 87 basis points over like maturity Treasuries.

Treasury yields moved substantially higher with two, five, ten and thirty-year maturities climbing by 35, 80, 68 and 27 basis points, respectively, with most of the Treasury market move occurring in the first half of the annual period. In fact, if measured as a standalone period, the second half of the annual period resulted in lower Treasury yields across long-maturity terms. This is, in part, driven by lower long-term growth and inflation expectations. Although the Fed has changed its methodology on inflation targeting, inflation has been running well above its "2% over time" target for months, and policy tightening is expected to lead to slower growth potential. The corporate components of the Bloomberg US Aggregate Bond Index led with a 2.2% return, government-related securities returned 0.0%, securitized products delivered a -0.5% return, and Treasuries trailed other sectors returning -2.5%.

Calamos Total Return Bond Fund

The Fund held an overweight in corporate debt over the annual review period. The overweight allocation to corporate bonds in industrial sectors was a contributor to performance, as was the security selection among the same issuers. Security selection among the Fund's positions in both Treasury and mortgage-backed securities weighed on performance. The team increased the corporate-bond allocation during the annual period, and over the long-term, we continue to favor an overweight to corporate bonds and asset-backed securities in the Calamos Total Return Bond Fund because the additional yield has historically helped generate superior long-term returns.

How is the Fund positioned?

The Fund has a duration of 6.1 years, short of the 6.7-year duration of the Bloomberg US Aggregate Bond Index.

The Fund continues to hold an overweight in corporate bonds in both the investment-grade and out-of-benchmark high-yield ratings categories. These overweights lead to a lower overall credit quality of A when compared with the AA- quality of the benchmark. The sell-off in Treasury rates coupled with the tightening of spreads in risk assets led to slightly positive returns during the annual period, behind the peer-group average and ahead of the Bloomberg US Aggregate Bond Index. The Fund continues to hold overweight positions in corporate and asset-backed securities and underweight positions in Treasuries and Agencies following the changes. Within the corporate-bond allocation, our largest overweight allocations are found in the consumer non-cyclical and REITs sectors.

What are your closing thoughts for Fund shareholders?

In some ways, fixed-income markets at the end of the annual period look quite similar to the environment from earlier this year, but there are significant changes at play impacting our outlook on where interest rates and credit markets are headed into the last months of 2021, not least of which is our expectation of greater volatility, particularly in Treasury yields, in coming months and quarters.

One source of potential volatility was related to the leadership of the Federal Reserve. Jerome Powell's first term as Chair ends in early 2022 and following the resignation of two Federal Reserve presidents over ethical concerns related to personal trading, President Biden was pressured not to renominate Powell. A change at the helm of the Fed could have led to unknown shifts in policy or forward guidance. At the time of this writing in November, however, the president did renominate Powell to another four-year term, citing Powell's deft leadership in guiding the economy through the pandemic-induced recession and subsequent recovery. Uncertainty around fiscal policy is another potential driver of fourth-quarter 2021 interest-rate volatility. With an unknown price tag or timeline for approval of a social spending package, the market is left to hypothesize what the related inflationary pressure might be. One thing is certain: even in a much-reduced form, no one will characterize the budget as austere.

Inflation will drive nominal GDP growth significantly higher as the economy moves from above-trend inflation driven by transitory factors to stickier components, namely shelter and wages. Despite higher-than-trend inflation expectations, we believe real interest rates will remain in negative or very low territory, which will support risk assets including investment-grade and high-yield credit markets.

Spreads in risk assets are trading near all-time tights, and although we do not see a catalyst for materially wider levels from here, further tightening at a broad level will prove more difficult. Our base case anticipates tight trading ranges in the coming quarter or two, emphasizing the need for active management and our bond-by-bond-driven investment philosophy.

Calamos Total Return Bond Fund

ANNUALIZED RETURN: SINCE INCEPTION (6/27/07) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measure net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

Duration is useful in measuring a bond fund's sensitivity to changes in interest rates. The longer the duration, the more a bond fund's price will fluctuate when interest rates change.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos Total Return Bond Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.04%, Class C shares is 1.78% and Class I shares is 0.78%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 0.90%, 1.65%, and 0.65% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 2.25% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graph does not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The Bloomberg US Aggregate Bond Index is considered generally representative of the investment-grade bond market.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos High Income Opportunities Fund

OVERVIEW

Through its multi-sector fixed-income strategy, the Fund invests mainly in high-yield securities from US issuers with the goal of generating a high level of current income and total return in excess of the benchmark index over full market cycles.

KEY FEATURES

ⁿ  Employs bond-by-bond portfolio construction with a focus on being well compensated for risks taken. We believe a disciplined process, grounded in fundamental research, enables us to achieve higher total returns with less volatility.

ⁿ  Draws on broader investable universe to enhance portfolio construction and risk management. Expanding the universe to include bank loans and preferred securities provides additional opportunities.

ⁿ  Utilizes robust, independent credit research. Our fixed-income investment process unites quantitative and qualitative analyses into historical and forward-looking models. The result is a credit rating that reflects where a company is heading.

ⁿ  Applies a macro overlay to capitalize on opportunities in misunderstood industries and sectors. The overlay acts as a risk control that also considers the business cycle, geopolitics, inflation and real rate expectations.

PORTFOLIO FIT

The Fund can complement investment-grade credit exposure, providing attractive income and total return potential for more risk-tolerant investors.

FUND NASDAQ SYMBOLS

CALAMOS HIGH INCOME
OPPORTUNITIES FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), the Fund returned 13.16% (Class I shares at net asset value) versus a gain of 10.53% for the Bloomberg US Corporate High Yield 2% Issuer Capped Index.

Since its Class I shares inception on March 1, 2002, the Fund gained 6.41% on an annualized basis versus an 8.01% return of the Bloomberg US Corporate High Yield 2% Issuer Capped Index.

What factors influenced performance during the annual period?

Record corporate earnings, strong economic growth, a reopening economy, investor optimism and extraordinary fiscal and monetary stimulus provided an atmosphere that supported strong performance across risk assets over the annual period. Equity markets across capitalizations and geographies delivered robust returns, while credit spreads in developed economies traded near all-time tights, reflecting historically low default rates and continued economic expansion.

Although Covid lingers and variants of the virus continue to pose a threat, vaccination progress continues. Tens of millions of shots are being administered daily worldwide, and nearly 50% of the global population has now been fully vaccinated. Fiscal policy has always been an important consideration for investors, but the size and scope of Covid-related relief packages introduced over the annual period have been exceptional. While not specifically associated with Covid, further government spending packages, including the recently passed $1 trillion infrastructure bill, will inject massive sums into the domestic economy.

Calamos High Income Opportunities Fund

Over the course of the annual period, the Federal Reserve also provided a remarkable level of monetary stimulus by holding its overnight borrowing rate at 0.0% while purchasing over $1 trillion of Treasury and mortgage-backed securities to maintain easy financial conditions. Continued progress toward the Fed's goal of full employment is drawing us closer to a reduction of monetary stimulus, with the Fed expected to announce a taper of its asset purchases beginning in late 2021. Real interest rates, which measure the risk-free compensation an investor receives after inflation, have been negative since January 2020, providing support for risk assets. In 2010, real interest rates also crossed into negative territory, and remained there for 42 consecutive months, which helped fuel the longest economic expansion in post-WWII history. If real rates were to remain negative for a similar duration now, this scenario would extend into the middle of 2023. This consideration is one of the factors contributing to the market's optimism for continued above-trend expansion.

To be sure, challenges exist, and inflation is primary among them. Higher inflation eats into the financial benefit of economic growth, impacting the amount of real consumption by consumers. Headline inflation (inclusive of energy and food prices) is measuring above 5%, the highest rate in 30 years. Inflation related to wages and housing, which have historically been signals of stickier inflation, are also climbing higher indicating that inflation may not be as transitory as many hoped. One source of inflation has been ongoing supply-chain challenges stemming from the global economic shutdown that occurred at the onset of the Covid pandemic. The reopening of several industries has been stymied as component parts must be manufactured and delivered via congested ports and understaffed trucking companies. Despite these challenges, consumer demand, as measured by personal spending and GDP growth, is expanding at healthy levels, informing the market's expectations for continued strength.

During the first half of the annual period, corporate-credit markets continued to enjoy a rapid recovery from the height of the pandemic, collapsing from more than 500 basis points over like-maturity Treasuries to inside of 300 basis points. A tight trading range has been established since April, with spreads fluctuating in a 50-basis-points range between 265 and 315 basis points. Issuance volumes have trended lower in recent months but remain historically high with 2021 poised to be the largest volume year on record. The Bloomberg US High Yield 2% Issuer Capped Index closed the annual period with option-adjusted spreads at 288 basis points over like-maturity Treasuries, and a yield of 4.24%.

Performance during the annual period was directional, with lower quality CCC-rated issuers delivering returns of 18.2%, trailed by B-rated issuers at 9.2% and BB companies returning 9.1%. At the beginning of the annual period, the trailing 12-month default rate was 6.3%, largely driven by energy-related businesses in both exploration and production and oil field services. At the end of the period, default rates had declined to 0.4%, the second lowest level in history following December 2007. Regarding our credit-quality positioning, our underweight to BB-rated bonds positively contributed to performance, while security selection among our CCC-rated holdings was a detractor.

FUND CUSIP NUMBERS

SECTOR WEIGHTINGS

Sector weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

Calamos High Income Opportunities Fund

From a sector perspective, security selection within the energy and consumer non-cyclical sectors contributed to return. Conversely, the Fund's underweight to the energy sector and overweight to the insurance sector weighed on performance.

How is the Fund positioned?

The Fund is currently overweight to the property and casualty insurance, pharmaceuticals, and other REITs industries. The property and casualty insurance overweight is correlated to favorable consolidation trends in the industry. The pharmaceuticals overweight is a result of the team's idiosyncratic positioning among a small number of companies with improving fundamental results. Our largest underweights are found in the wireless, electric utilities and independent energy industries. The wireless sector underweight is largely the result of relative value decisions in favor of higher-income opportunities in other industries.

From a credit-quality perspective, the Fund is positioned with a relative underweight in the BB category, while currently overweight toward both B-rated and CCC-rated issuers. The Fund is positioned short (3.4 years) in comparison with the option-adjusted duration of the Bloomberg US High Yield 2% Issuer Capped Index (4.0 years).

Over the annual period, the team has added to positions in the media entertainment, airlines, and technology industries. Also, we reduced the portfolio's exposure to health care, wireless and independent energy industries. The increases in media entertainment and airlines represent what we believe to be strong relative value positions emerging from the Covid pandemic. The reduction in health care was primarily due to closing a profitable trade that had reached our target valuation.

What are your closing thoughts for Fund shareholders?

In some ways, fixed-income markets at the end of the annual period look quite similar to the environment from earlier this year, but there are significant changes at play impacting our outlook on where interest rates and credit markets are headed into the last months of 2021, not least of which is our expectation of volatility, particularly in Treasury yields, in coming months and quarters.

One source of potential volatility was related to the leadership of the Federal Reserve. Jerome Powell's first term as Chair ends in early 2022 and following the resignation of two Federal Reserve presidents over ethical concerns related to personal trading, President Biden was pressured not to renominate Powell. A change at the helm of the Fed could have led to unknown shifts in policy or forward guidance. At the time of this writing in November, however, the president did renominate Powell to another four-year term, citing Powell's deft leadership in guiding the economy through the pandemic-induced recession and subsequent recovery. Uncertainty around fiscal policy is another potential driver of fourth-quarter 2021 interest-rate volatility. With an unknown price tag or timeline for approval of a social/climate spending package, the market is left to hypothesize what the related inflationary pressure might be. One thing is certain: even in a much-reduced form, no one will characterize the budget as austere.

Inflation will drive nominal GDP growth significantly higher as the economy moves from above-trend inflation driven by transitory factors to stickier components, namely shelter and wages. Despite higher-than-trend inflation expectations, we believe real interest rates will remain in negative or very low territory, which will support risk assets including investment-grade and high-yield credit markets.

Calamos High Income Opportunities Fund

Spreads in risk assets are trading near all-time tights, and while we do not see a catalyst for materially wider levels from here, further tightening at a broad level will prove more difficult. Our base case anticipates tight trading ranges in the coming quarter or two, emphasizing the need for active management and our bond-by-bond-driven investment philosophy.

ANNUALIZED RETURN: SINCE INCEPTION (3/1/02) THROUGH 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted.

The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost. You can obtain performance data current to the most recent month end by visiting www.calamos.com. Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average. All performance shown assumes reinvestment of dividends and capital gains distributions. Performance is for the Fund's Class I shares at net asset value. The Fund also offers Class A and Class C shares, the performance of which may vary. Source: State Street Corporation and Morningstar Direct.

*  Annual returns for Class I shares are provided because Class I shares represent the largest percentage of assets in the Calamos Family of Funds.

Calamos High Income Opportunities Fund

GROWTH OF $1,000,000: FOR THE 10-YEAR PERIOD ENDED 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 1.37%, Class C shares is 2.11% and Class I shares is 1.12%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through March 1, 2023, to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A, Class C, and Class I are limited to 1.00%, 1.75%, and 0.75% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expenses limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 2.25% for Class A shares and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The graphs do not reflect the income taxes that you would pay on fund distributions or the redemption of fund shares. Fund performance includes reinvestment of dividends and adjustment for the maximum sales charge for Class A shares. The performance of other classes will vary from the performance of the class shown based on the difference in sales charges and fees paid by shareholders investing in different share classes.

The Bloomberg US Corporate High Yield 2% Issuer Capped Index measures the performance of high-yield corporate bonds with a maximum allocation of 2% to any one issuer.

Index returns assume reinvestment of dividends and do not reflect deduction of fees and expenses. It is not possible to invest directly in an index.

Calamos Short-Term Bond Fund

CALAMOS SHORT-TERM BOND FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the 12 months ended October 31, 2021 ("annual period"), the Fund returned 1.11% (Class I shares at net asset value) outperforming the -0.05% return of the Bloomberg 1-3 Year Government/Credit Bond Index.

Since its inception on September 19, 2018, the Fund has returned 3.15% on an annualized basis (Class I share at net asset value) versus the 2.68% return of the Bloomberg 1-3 Year Government/Credit Bond Index.

What factors influenced performance during the annual period?

Record corporate earnings, strong economic growth, a reopening economy, investor optimism, and extraordinary fiscal and monetary stimulus provided an atmosphere supportive of strong performance across risk assets over the annual period. Equity markets across capitalizations and geographies delivered robust returns, while credit spreads in developed economies traded near all-time tights, reflecting historically low default rates and continued economic expansion.

Although Covid lingers and variants of the virus continue to pose a threat, vaccination progress continues. Tens of millions of shots are being administered daily worldwide, and nearly 50% of the global population has now been fully vaccinated. Fiscal policy has always been an important consideration for investors, but the size and scope of Covid-related relief packages introduced over the annual period have been exceptional. While not specifically associated with Covid, further government spending packages, including the recently passed $1 trillion infrastructure bill, will inject massive sums into the domestic economy.

Over the course of the annual period, the Federal Reserve also provided a remarkable level of monetary stimulus by holding its overnight borrowing rate at 0.0% while purchasing over $1 trillion of Treasury and mortgage-backed securities to maintain easy financial conditions. Continued progress toward the Fed's goal of full employment is drawing us closer to a reduction of monetary stimulus, with the Fed expected to announce a taper of its asset purchases beginning in late 2021. Real interest rates, which measure the risk-free compensation an investor receives after inflation, have been negative since January 2020, providing support for risk assets. In 2010, real interest rates also crossed into negative territory, and remained there for 42 consecutive months, which helped fuel the longest economic expansion in post-WWII history. If real rates were to remain negative for now, this scenario would extend into the middle of 2023. This consideration is one of the factors contributing to the market's optimism for continued above-trend expansion.

To be sure, challenges exist, and inflation is primary among them. Higher inflation eats into the financial benefit of economic growth, impacting the amount of real consumption increases experienced by consumers. Headline inflation (inclusive of

OVERVIEW

Through its multi-sector fixed-income strategy, the fund invests predominantly in US issuers with the goal of generating a high level of current income and total return in excess of the benchmark over full market cycles.

KEY FEATURES

ⁿ  Employs bond-by-bond portfolio construction with a focus on being well compensated for risks taken. We believe a disciplined process, grounded in fundamental research, enables us to achieve higher total returns with less volatility.

ⁿ  Draws on a broader investable universe to enhance portfolio construction and risk management. Expanding the universe to include high-yield bonds, bank loans and preferreds provides additional opportunities.

ⁿ  Utilizes robust, independent credit research. Our fixed-income investment process unites quantitative and qualitative analyses into historical and forward-looking models. The result is a credit rating reflective of where a company is heading.

ⁿ  Applies a macro overlay to capitalize on misunderstood industries and sectors. The overlay acts as a risk control that also considers the business cycle, geopolitics, inflation and real rate expectations.

PORTFOLIO FIT

The Fund may be suitable for investors seeking current income accompanied by lower volatility over a one-year to two-year time horizon.

FUND NASDAQ SYMBOLS

Calamos Short-Term Bond Fund

FUND CUSIP NUMBERS

ASSET ALLOCATION

Asset Allocation weightings are subject to change daily and are calculated as a percentage of net assets. The table excludes cash or cash equivalents, any government/sovereign bonds or broad based index hedging securities the Fund may hold.

energy and food prices) is measuring above 5%, the highest rate in 30 years. Inflation related to wages and housing, which have historically been signals of stickier inflation, are also climbing higher indicating that inflation may not be as transitory as many hoped. One source of inflation has been ongoing supply chain challenges stemming from the global economic shutdown that occurred at the onset of the Covid pandemic. The reopening of several industries has been stymied as component parts must be manufactured and delivered via congested ports and understaffed trucking companies. Despite these challenges, consumer demand as measured by personal spending and GDP growth is expanding at healthy levels, informing the market's expectations for continued strength.

Short-duration Treasury yields out to two years were relatively unchanged over the course of the annual period, although two-year rates increased by 35 basis points. This move occurred almost entirely in the last two months of the annual period, as expectations for a more aggressive taper and tightening path for the Fed took hold in the market, though no Fed communication would indicate a change from its latest projections indicating a 2023 liftoff for overnight rates.

The corporate component of the Bloomberg 1-3 Year Government/Credit Bond Index led with a 0.6% return, while the government-related sector returned 0.0%, and Treasury sectors trailed at -0.3%. The Fund held an overweight in corporate debt over the annual period. As a result, the overweight allocations to corporate bonds across financial, industrial and utility-related sectors were positive contributors to performance. The out-of-benchmark allocation to below-investment-grade credit also boosted performance as the short-duration, high-yield market recovered quickly from the spike in spreads during the first calendar quarter of 2020. Over the long-term, we continue to favor an overweight to corporate bonds, asset-backed securities, and taxable municipal bonds in the Calamos Short-Term Bond Fund because the additional yield in short-duration securities has historically helped generate superior long-term returns.

How is the Fund positioned?

The Fund has a duration of 2.0 years versus the 1.9 years duration of the Bloomberg 1-3 Year Government/Credit Bond Index.

The Fund continues to hold an overweight in corporate bonds in both the investment-grade and out-of-benchmark high-yield ratings categories. These overweights lead to a lower overall credit quality of A- when compared with the AA quality of the benchmark. The selloff in two- and three-year Treasury rates coupled with the recovery of credit spreads in risk assets since March 2021 led to positive Fund returns during the annual period. The Fund remains overweight to corporate bonds and asset-backed securities. However, the weighting of corporate bonds was decreased during the most recent six-month period, as the team has moved into higher-yielding opportunities in term loans and taxable municipal bonds. The term-loan positions are floating rate in nature, which helps mitigate exposure to increases in short-term interest rates. The Fund continues to hold underweight positions in both Treasuries and Agencies. Within the corporate bond allocation, our largest overweight allocations are found in the consumer non-cyclical and technology sectors.

Calamos Short-Term Bond Fund

What are your closing thoughts for Fund shareholders?

In some ways, fixed-income markets at the end of the annual period look quite similar to the environment from earlier this year, but there are significant changes at play impacting our outlook on where interest rates and credit markets are headed into the last months of 2021, not least of which is our expectation of greater volatility, particularly in Treasury yields, in coming months and quarters.

One source of potential volatility was related to the leadership of the Federal Reserve. Jerome Powell's first term as Chair ends in early 2022 and following the resignation of two Federal Reserve presidents over ethical concerns related to personal trading, President Biden was pressured not to renominate Powell. A change at the helm of the Fed could have led to unknown shifts in policy or forward guidance. At the time of this writing in November, however, the president did renominate Powell to another four-year term, citing Powell's deft leadership in guiding the economy through the pandemic-induced recession and subsequent recovery. Uncertainty around fiscal policy is another potential driver of fourth-quarter 2021 interest-rate volatility. With an unknown price tag or timeline for approval of a social/climate spending package, the market is left to hypothesize what the related inflationary pressure might be. One thing is certain: even in a much-reduced form, no one will characterize the budget as austere.

Inflation will drive nominal GDP growth significantly higher as the economy moves from above-trend inflation driven by transitory factors to stickier components, namely shelter and wages. Despite higher-than-trend inflation expectations, we believe real interest rates will remain in negative or very low territory, which will support risk assets including investment-grade and high-yield credit markets.

Spreads in risk assets are trading near all-time tights, and while we do not see a catalyst for materially wider levels from here, further tightening at a broad level will prove more difficult. Our base case anticipates tight trading ranges in the coming quarter or two, emphasizing the need for active management and our bond-by-bond-driven investment philosophy.

Calamos Short-Term Bond Fund

GROWTH OF $1,000,000: SINCE INCEPTION (9/18/18) THROUGH 10/31/21

AVERAGE ANNUAL TOTAL RETURN^† AS OF 10/31/21

Performance data quoted represents past performance, which is no guarantee of future results. Current performance may be lower or higher than the performance quoted. The principal value and investment return of an investment will fluctuate so that your shares, when redeemed, may be worth more or less than their original cost.

As of the prospectus dated 3/1/21, the Fund's gross expense ratio for Class A shares is 0.68% and Class I shares is 0.42%. The Fund's investment adviser has contractually agreed to reimburse Fund expenses through 3/1/23 to the extent necessary so that Total Annual Fund Operating Expenses (excluding taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, and extraordinary expenses, if any) of Class A and Class I are limited to 0.65% and 0.40% of average net assets, respectively. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the respective Fund's expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking is binding on Calamos Advisors and any of its successors and assigns. This agreement is not terminable by either party. The expense ratios shown above may differ from the more recent expense ratios reported in the Financial Highlights section of this report.

†  Average annual total return measures net investment income and capital gain or loss from portfolio investments as an annualized average assuming reinvestment of dividends and capital gains distributions. Performance shown reflects the effects of an expense reimbursement that improved results. Load-adjusted returns are adjusted for the maximum front-end sales load of 2.25% for Class A shares.

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