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

TIMELY INFORMATION INSIDE

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Family of Funds

SEMIANNUAL REPORT APRIL 30, 2022

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

Calamos International Small Cap Growth Fund

Sustainable Equities

Calamos Global Sustainable Equities 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 20 mutual funds include equity, fixed income, convertible, alternative and sustainable equity 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 semiannual report for the six months ending April 30, 2022. In this report, you will find commentary from our portfolio management teams, a listing of portfolio holdings, financial statements and highlights, and detailed information about the performance and positioning of the Calamos Funds.

Before we explore the markets, economy, and funds at greater length, all of us at Calamos Investments thank you for your continued trust. There is no doubt the current market environment is challenging. In the newsfeeds, discouraging headlines—rising interest rates, oil prices, inflation, supply chain issues—have tended to overshadow more positive data, such as strong corporate earnings, improving employment data, and good consumer balance sheets.

In uncertain times, it is often easy to forget all the unprecedented hurdles that the economy has navigated. I began my investing career more than 50 years ago in the difficult financial markets of the 1970s, a time characterized by soaring inflation; rising interest rates; difficult conditions across asset classes; and geopolitical uncertainties, including the Cold War. Through the ensuing decades, I've seen there are long-term investment opportunities in all environments.

Although no interest rate, market or economic cycle is exactly like the last, we are confident in the long-term resilience of the global economy. More important, we are confident in our ability to turn market volatility into long-term opportunities for the shareholders of the Calamos Funds—through a variety of environments.

Market Review

During the semiannual period, surging volatility and sharp rotations roiled global financial markets. Russia's invasion of Ukraine, a decidedly more hawkish stance from the Federal Reserve, rising interest rates, and Covid-19 lockdowns in China exacerbated investors' longer-term anxieties about inflation, supply chains, commodity shortages, and interest rates. Oil prices soared, and the yield of the 10-year US Treasury spiked upward, as did mortgage rates.

Letter to Shareholders

Against this backdrop, few areas of the global capital markets remained unscathed, and stock, bond, and convertible security markets retreated.* As emotions ran high, even fundamentally strong companies experienced sharp sell-offs.

Outlook

These next months will continue to test the resolve of investors. We are prepared for persistent market volatility and saw-toothed market performance that may include some more sharp sell-offs. The current headline issues are each enough to cause powerful crosscurrents, and the markets must navigate them all. Moreover, as midterm elections in the US approach, we expect the uncertain US fiscal policy backdrop will add to market participants' already heightened apprehension. Against this backdrop, we are likely to see sentiment-driven market behavior, where strong companies with good potential will also face pressure.

We believe our active management provides a considerable advantage in a market environment driven by emotional decision-making and a short-term perspective. Although markets are generally efficient over the long term, they may be anything but efficient over the short term, which can create opportunities for experienced investors with long-term horizons.

Asset Allocation Considerations

Unfortunately, no one can predict the short-term twists and turns in the market. The best strategy is to maintain a long-term perspective and not give in to the temptation to try to time the market. With stock and bond markets likely to continue in a saw-toothed fashion, making significant short-term shifts in your asset allocation can be dangerous, particularly if your financial goals and risk tolerance haven't changed. Too often, when investors let emotion and short-term perspective drive decisions, they catch the downside and miss the upside.

Also, it's important to remember that investment performance is most effectively measured over years and the course of market, economic, and interest rate cycles. In periods like these, a lot can happen over the short term: days, weeks, or months. Many investments may even have episodes of short-term performance that are anomalous with long-term results. For these reasons, it's essential to assess results over extended periods. For example, the convertible securities market is one area that has demonstrated unusual performance over the short term. However, we believe the long-term case for convertibles remains intact and that our active management positions us well to turn volatility into opportunity.

Letter to Shareholders

I encourage you to revisit your investment portfolio to ensure it aligns with both your long-term goals and your risk tolerance. Be sure that your portfolio is well-diversified and seek out opportunities to learn how you can enhance that diversification to reflect your unique needs. Depending on your personal circumstances, this could include adding an alternative fund to potentially improve the overall risk/reward characteristics of your asset allocation. Alternatives can be used on either the equity or fixed income side of an asset allocation (e.g., Calamos Phineus Long/Short Fund and Calamos Hedged Equity Fund are equity alternatives, and Calamos Market Neutral Income Fund is a fixed income alternative). Our alternative funds can employ a broader set of strategies to navigate markets or interest rates than traditional funds, and like all of our funds, they are managed with keen attention to adjusting to market risks and opportunities.

Given the crosscurrents of market volatility, inflation and rising interest rates, allocations to funds that invest in short-term bonds may be compelling. Calamos Short-Term Bond Fund invests in short-duration credits to pursue a high level of current income consistent with capital preservation. Through this approach, the fund may provide an attractive way to put cash to work with less exposure to interest rate risk than longer-term bonds.

Allocations to Calamos funds that invest in convertible securities may also prove advantageous. Convertibles are hybrid securities that offer unique opportunities versus stocks and bonds over the course of full market and interest rate cycles. I first began using convertible securities in the 1970s, and they offered what I viewed as a "best of both worlds" approach versus stocks and bonds, which I've seen through the decades since. This report includes commentary on an array of funds that use convertibles to pursue enhanced risk and reward, including Calamos Convertible Fund, Calamos Growth and Income Fund, and their global counterparts, Calamos Global Convertible Fund and Calamos Global Opportunities Fund.

Conclusion

With so many variables shaping the markets right now, staying focused on the long term is paramount. It wasn't that long ago that people thought the Covid-19 pandemic would change the way businesses operated and people interacted forever, and global markets overreacted to the downside. Markets sprang back in a similarly dramatic fashion as pandemic fears receded. Although it may be difficult for investors, it is not surprising that markets are now moderating from these heights.

In the midst of these sorts of short-term swings, we believe our teams' decades of experience in the markets and our active, risk-managed approaches will allow us to position the funds advantageously. In these fast-moving markets, our teams rely on discipline and a long-term perspective to manage downside risks and pursue opportunities across asset classes.

Letter to Shareholders

To learn more about Calamos Investments' views of the economy, markets and asset allocation, please visit our website, www.calamos.com. We thank you for your continued trust.

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 six months ended April 30, 2022: The S&P 500 Index, a measure of the US stock market, returned -9.65%. The MSCI All Country World Index, a measure of global stock market performance, returned -11.45%. The ICE BofA All US Convertibles Index, a measure of the US convertible securities market, returned -15.19%. The Refinitiv Global Convertible Bond Index, a measure of the global convertible bond market, returned -16.33%. The Bloomberg US Corporate 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 -7.40%. The Bloomberg US Aggregate Bond Index, a measure of the US investment-grade bond market, returned -9.47%, the Bloomberg US Government/Credit 1-3 Year Index, a measure of US short-term bond performance, returned -3.24%.

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. The Fund also uses opportunistic strategies to augment the main strategies: SPAC arbitrage offers a source of cheap optionality, and merger arbitrage offers a high probability of positive returns over a longer time horizon.

Calamos Market Neutral Income Fund is designed to:

^◼  Potentially enhance an investor's fixed-income allocation.

^◼  Actively pursue equity market upside while hedging downside risk.

^◼  Provide consistent absolute total return over varying market cycles.

In addition to offering an attractive historical risk/reward profile, the Fund may enhance long-term portfolio diversification potential, a vital benefit given recent bouts of elevated equity volatility.

How has the Fund performed?

For the six months ended April 30, 2022 ("semiannual period"), Calamos Market Neutral Income Fund returned -2.98% (Class I Shares at net asset value), strongly outperforming the -9.92% loss for the Bloomberg US Government/Credit Bond Index, while trailing the 0.06% return of the Bloomberg Short Treasury 1-3 Month Index.

What factors influenced performance during the semiannual period?

The convertible and equity markets were challenged during the reporting period by Covid-19 variants, supply chain disruptions, the war in Ukraine, inflation, elevated oil prices and rising interest rates. Against this volatile backdrop, both stocks and bonds saw significant declines as represented by the S&P 500 Index (-9.65%) and Bloomberg US Government/Credit Bond Index (-9.92%). The Calamos Market Neutral Income Fund provided resiliency in an environment in which the only thing that seemed to increase were correlations. The realized volatility of the S&P 500 as measured by the Cboe Volatility Index (VIX) nearly doubled from 16.26 at the beginning of the period to 33.40 at the end.

Interest rates rose during the period as exemplified by the Bloomberg US Aggregate Bond Index yield to maturity increasing 127 basis points to 2.57%. In addition, global high yield corporate credit spreads widened 44 basis points to 423 basis points according to Bloomberg. These rising interest rates and widening credit spreads impeded the bond component of convertibles during the reporting period. Near-zero overnight interest rates through much of the period acted as a headwind to the carry on the cash received from short positions. This said, the recent 0.75% increase to the fed funds rate has turned our carry positive (our custodian rebates the fed funds rate less our roughly 35 basis points of borrowing costs on short holdings).

OVERVIEW

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

KEY FEATURES

^◼  Generates returns not dependent on interest rates, breaking from traditional bond strategies.

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

^◼  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 rising 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.

In this environment, the hedged equity strategy of the Fund was hurt by the S&P 500 market downturn given that the strategy's equity basket declined toward its put protection. While the elevated volatility in the market at times provided attractive option rebalancing opportunities and benefited from the higher level of implied volatility in the options market, these contributions weren't enough to overcome the magnitude of the decline during the reporting period.

The convertible arbitrage portion held up well and benefited from the periods of volatility over the past six months, providing opportunities to profit from convertible hedge rebalancing. New convertible issuance cooled during the period as the extreme volatility inhibited IPO activity across all asset classes. The $21.7 billion in new US Convertibles issuance was well off the near-record pace seen in 2020 and 2021.

The Fund's SPAC Arbitrage and Merger Arbitrage sleeves also held up well relative to the market declines.

How is the Fund positioned?

At the end of the reporting period, the Fund had 51.9% in its hedged equity strategy and 48.1% in its arbitrage strategies. The arbitrage strategies included 37.2% in convertible arbitrage, 9.3% in SPAC arbitrage, and 1.6% in merger arbitrage.

The Fund's hedged equity strategy increased slightly from 50.2% to 51.9% and finished the quarter with a delta hedge in line with our traditional hedge. In addition to the outright long put allocation we maintain in the Fund, we continue to find opportunities to utilize spreads.

The allocation to convertible arbitrage was trimmed during the period (from 43.0% at the beginning of the period to 37.2%), and the assets were redeployed to take advantage of attractive opportunities in the SPAC Arbitrage strategy, which has a similar return and risk profile to convertible arbitrage.

The SPAC arbitrage sleeve increased from 5.6% to 9.3%, reflecting attractive opportunities to purchase SPACs below the value of the cash held in trust, which provided an attractive yield to expiration while also providing the potential for upside should any of the SPAC sponsors announce an acquisition. We're using SPAC arbitrage as a way to support the Fund's historically lower risk profile and steady returns. The strategy, in essence, is creating a cheap option with a risk/reward opportunity similar to convertible arbitrage.

What are your closing thoughts for Fund shareholders?

The reporting period provided a proof point of the Fund's diversification benefit within an asset allocation. The period brought turbulent volatility and rising interest rates, and the Fund was able to outperform both the stock and bond markets.

Investors continue to be anxious about a myriad of headlines including geopolitical strife (Russia's invasion of Ukraine), persistent supply chain disruptions, high oil prices, rising interest rates, US Federal Reserve tapering, upcoming US midterm elections, and new Covid variants. These have all contributed to bouts of elevated

Calamos Market Neutral Income Fund

volatility. The Calamos Market Neutral Income Fund seeks to provide a stable positive return with a low standard deviation by monetizing the volatility that markets generate.

Many of our clients have expressed concerns about recent high inflation and rising interest rates. We expect Calamos Market Neutral Income Fund will continue to provide especially compelling benefits as a fixed income alternative.

Calamos Market Neutral Income Fund

ANNUALIZED RETURN: SINCE INCEPTION (5/10/00) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.15%, Class C shares is 1.90%, Class I shares is 0.90% and Class R6 shares is 0.84%. 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 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 Morningstar Relative Value Arbitrage Category is comprised of funds that seek out pricing discrepancies between pairs or combinations of securities regardless of asset class.

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

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

^◼  The investment team seeks to take advantage of market opportunities by 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 expo-sure, thereby improving the quality of the ride.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS HEDGED EQUITY FUND

INVESTMENT TEAM DISCUSSION

Funds Strategic Approach and Role in a Portfolio

The Fund utilizes an actively managed equity and options strategy, which can be positioned as a solution to replace the broken 60/40 stock/bond allocation—as the Fund has outpaced stocks, bonds, and consequently the 60/40 blend this year.

Our active approach to options strategy management serves as a critical differentiator versus peers who use less actively managed options-based strategies. During the semiannual period ending April 30, 2022, the Fund sought to provide better upside/downside asymmetry than long-only equities while dampening volatility within its equity sleeve using an active option overlay strategy versus traditional fixed income. The Fund's time-tested approach proved highly responsive to the period's volatile market conditions.

How has the Fund performed?

"Expect the unexpected" was the mantra of the semiannual period with S&P volatility in backwardation, meaning front month VIX futures were more expensive than the later-dated futures. This type of backwardation signals the expectation of outsized intra-day moves, 3.5% – 6.0% for example, which is a real challenge for most of our peers that take a more mechanistic hands-off approach.

This market environment presented both a challenge and an opportunity for the Fund's investment team. On the one hand, the increased volatility allowed the team to actively reposition long puts, put spreads, and short calls on big intra-day moves down. On the other hand, the team took profits on long calls with significant intra-day moves up. This active approach generated better total and risk-adjusted returns in the volatile period.

For the six months ended April 30, 2022 ("semiannual period"), Calamos Hedged Equity Fund was down -6.59% (Class I shares at net asset value) versus the S&P 500 Index -9.65% return and the Bloomberg US Aggregate Bond Index decrease of -9.47%. Since its inception on December 31, 2014, the Fund gained 5.84% (Class I shares at net asset value) on an annualized basis versus 12.08% for the S&P 500 Index and 1.47% for the Bloomberg US Aggregate Bond Index.

What factors influenced performance during the reporting period?

During the semiannual period, the market repeatedly tested a low around the highly watched 4200 level of the S&P 500 Index.¹ The market sold off with the start of the war in Ukraine in late February. The S&P 500 found a floor on March 8 when it closed at 4170. Following that bottom, stocks rallied, with the S&P 500 trading up to 4631 on March 29. Although we failed to challenge the all-time high found at the outset of 2022, this increase represented an 11% increase from bottom to top. During April, stocks again sold off, predominately due to fear of aggressive Federal Reserve tightening. Equities retested the S&P 4200 support level, closing at 4131 on April 29. That left the market at the time of writing below critical support, needing an immediate upside response to avoid a further breakdown.

Another factor that has begun to weigh on the market is contracting liquidity, posing a headwind for stocks and bonds. However, this contraction is coming on the heels of robust inflation, sparking a greater degree of hawkish Fed rhetoric. Markets have struggled as they price in very steep short-term interest rate expectations. Higher rate-increase expectations have also propelled bond yields

¹  All market data figures shown are sourced from Bloomberg.

Calamos Hedged Equity Fund

higher, inflicting additional pain on the 16-month bear market in bonds. The first two quarters of 2022 resulted in negative returns for both stocks and bonds, a rare double/double.

How is the Fund positioned?

The Fund midway through 2022 had less short call exposure (-40%) than we had in late 2021. The Fund has been positioned to the higher end of our guardrail long-put exposure of 60%. We took advantage of the volatility spikes in January and early March and hedged with attractive long-put spreads. To stay long leaning and keep the Fund's upside capture ratio close to 60% of the S&P 500 Index, the team used some of the excess premium budget to add upside long calls, with the notional short-call quantity less than 40%, thereby improving our upside participation potential. The current option implied volatility, and the equity market's volatility creates added challenges in capturing skew.* Option-implied volatility escalated considerably toward the end of the period, and we expect the VIX's actual volatility to stay at these escalated levels. With the VIX curve continuing to vacillate into backwardation, front-month futures higher than the back month, we should expect more extensive intra-day moves, 3% – 5% swings. Considering that equities continued to challenge the lows and realized volatility has been materially higher for a while (apart from some recent drops), we expect to stay on the lower end of our beta budget, which is 49 – 50.

Should equity markets advance, the Fund's options positioning is poised to participate in the upside while also providing an enhanced income stream from call spreads and equity dividends. Conversely, if the markets retreat, the dividend plus short-call income stream and the puts/put spreads used in the Fund will mitigate the potential downside.

We use rallies to replace some of our put hedges with long-put spreads, which appear more attractive. At the end of the period, the Fund's net long put representation was 60%, with an average strike of 4123. Our short-call positioning included a call write of -38%, with an average strike of 4558.

At the end of the reporting period and relative to the S&P 500 Index, our sector positioning was slightly overweight in the consumer discretionary and information technology sectors. The portfolio slightly underweighted the materials, financials, consumer staples, real estate, and materials sectors. Relative to the S&P 500 Index, the Fund's market-cap positioning maintained a heavier relative weight to larger capitalization (>$25 billion) holdings and a lighter weight to small and mid-capitalization ($1 to $25 billion).

What closing thoughts do you have for Fund shareholders?

The team will continue to look to add upside exposure at nearby support if it is held at the current levels or closer to 3800 SPX if the current level does not hold. Longer-term, there is a solid case for adding exposure immediately, but momentum can take markets further than commonly thought in the short term. In order to have a higher conviction short term, we want to see that downside momentum broken.

Besides commodities, volatility has been the timeliest asset class over the last 12 months. This year has been particularly challenging as both stocks and bonds

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 as a statistical data set. 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 S&P 500 tail risk price is calculated from the S&P 500 out-of-the-money options prices.

Calamos Hedged Equity Fund

have posted negative results, highlighting a massive problem in the mechanical method of asset allocation, commonly known as 60/40. Our disciplined approach of actively managing our hedged equity strategy² has provided a solution to replace the broken 60/40 stock/bond allocation—outpacing stocks, bonds, and, consequently, the 60/40 blend this year.³ Indeed, longer-term, annualized returns over the last 36 months have almost equaled global equities with just a little over half the risk as measured by drawdown. As priced in an elevated Cboe Volatility Index (VIX), an elevated level of fear provides a good springboard for us to harvest that spiking price in volatility, driving better total and risk-adjusted returns.

²  Semiannual period as of April 30, Calamos Hedged Equity Fund Class I shares (-6.59%), S&P 500 Index (-9.65%), Bloomberg US Aggregate Bond Index (-9.47%) all six months.

³  Semiannual period as of April 30, the 60/40 S&P US Aggregate Bond Index rebalanced monthly (-9.46%).

GROWTH OF $1,000,000: SINCE INCEPTION (12/31/14) THROUGH 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.18%, Class C shares is 1.93% and Class I shares is 0.93%.

†  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 March 31, 2021. 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:

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

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

^◼  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 six months ended April 30, 2022 ("semiannual period"), Calamos Phineus Long/Short Fund returned 0.00% (Class I shares at net asset value), outperforming the S&P 500 Index -9.65% return and the MSCI World Index -11.11% return over the same period.

Since its inception on May 1, 2002, the Fund has returned 10.49% on an annualized basis (Class I shares at net asset value) and, thus, markedly outperformed both the S&P 500 Index and MSCI World Indexes, which returned 9.09% and 8.05%, respectively, over the since inception period. As of April 30, 2022, the long/short portion of the portfolio had a delta-adjusted^† net long position of approximately 49%.

What factors influenced performance during the semiannual period?

The Fund's outperformance relative to the global indices largely reflected the Fund's underweight exposure to the equity derivatives of long duration. The Fund concluded April with an average net equity delta-adjusted exposure of 50.4%, which compares to its average net equity exposure of 27% (on a cash basis)^† since inception in 2002.

The semiannual period was extraordinary by most standards, culminating in the sad conflict between Russia and Ukraine. While this geopolitical crisis has created widespread dissonance, it should be viewed as the second and lesser of the two shocks that have buffeted investors in 2022.

The more important shock has been the repricing of developed world debt led by the US Federal Reserve. This resulted in the most rapid rise of US debt yields since the bond market crash of 1994. Within six months, the Federal Reserve has

OVERVIEW

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

KEY FEATURES

^◼  Fundamental global process blends top-down and bottom-up considerations.

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

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

^◼  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 an equity portfolio.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

†  When the portfolio management team evaluates the Fund's exposures and related risks, they include calculations based on a delta-adjusted basis, which 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 that point in time since a security's delta changes continuously with market activity. The investment team began calculating the Fund's exposure on a delta-adjusted basis in August 2008.

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.

moved from "transient inflation" to "upside inflation risk," with fed funds futures now discounting a funds rate near 3% by March 2023. Having learned not to fight the Fed, investors fear rising recession risk, which has been visible in the relative performance of industries and styles.

Fund performance amid all of these developments was respectable in both absolute and relative terms, particularly in calendar Q1 2022. First, we have been wary of the equity derivatives of long duration for much of the past year. In December 2021, we further distanced the portfolio from long-duration growth and defensive areas. Examples here include the sale of Facebook and Salesforce as well as short strategies in names like Netflix and PayPal.

We added additional index hedges in January 2022 that cushioned our clients from the initial stages of the market retreat, with the result that both the long and short books have been additive to performance. The re-orientation of the Federal Reserve, which became apparent with the release of the December FOMC minutes, was the signal that we should no longer lean aggressively into equity risk.

What helped and hurt performance over the semiannual period?

The Fund's largest contributors were long investments in the energy and materials sectors, while long positions in financials, industrials and information technology hindered performance. Notable contributors during the period included a short position/hedge on the SPDR S&P 500 ETF TRUST -48.41%* and long positions in Canadian Natural Resources 1.69% average weight over period (energy) and Baker Hughes 1.85%* (energy). Detractors included long positions in Twilio Inc. 2.06%* (information technology), Boeing Company 2.97%* (industrials) and Caesars Entertainment Inc. 2.52%* (consumer discretionary).

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

Net equity exposure (delta-adjusted) concluded the semiannual period at 48.7% versus 57.2% at the start of the period. This compares with the average net equity exposure of 27% (cash basis) since inception in 2002. The Fund leaned modestly into equity risk through April as markets became unsettled by higher interest rates and the outbreak of war in Ukraine.

One key conviction has been our cautious view on duration and its equity derivatives. This translates into the bias toward shorter duration, more profitable businesses versus those with less support from earnings, cash flow and tangible assets or book value. We have been wary of stocks where the bulk of their value depends on assumptions about growth in the far future. This sheltered the Fund from some of the most egregious stock disappointments of the period.

Equally important has been our preference for services over goods as the world emerges from the pandemic. This implies a robust recovery in travel and entertainment along with a return to the office. Both producers and retailers of goods will struggle in real terms (volume rather than price) well into 2023. We think the pandemic pulled forward years of demand across varied industries and this will take time to digest.

The Fund favors names perceived as more cyclical with recovery potential in the coming year. The broadest exposures for the long book are industrials and transports followed by financials.

*  04/30/22 % Delta-Adjusted Net Exposure

Calamos Phineus Long/Short Fund

Our bias within industrials remains focused upon commercial aerospace, airlines and other transports, and defense names. The recent recovery in leisure air travel should be followed by a slower-but-sustained increase in corporate and international travel later this year and into next. Airlines are restrained for capacity expansion due to shortages of labor and planes; the pricing environment should remain firm for the foreseeable future. We prefer higher quality over both low-cost carriers and those with heavy debt loads heading into a higher-rate environment.

We like the railroads as US-centric beneficiaries of supply chain normalization. Their business models are levered to higher inflation and a tight commodity environment, yet with limited exposure to cost pressures from labor or energy prices.

Thematically, the long portfolio remains focused on companies that benefit from higher long and short rates; companies with sufficient pricing power to pass along higher input costs to customers; companies with reasonably valued and sustainable growth; and companies set to benefit from the reopening trade such as pent-up demand among consumers for travel and recreation outside the home.

Energy was the largest contributor to performance in the long book. Although we don't anticipate further upside to crude prices in 2022, we expect high prices to be sustained, allowing producers to generate healthy cash flows given years of underinvestment. While we reduced our exposure to energy after the Putin shock, the long-term drivers supporting the industry remain firmly in place. Producers are maintaining a disciplined approach to capital spending, while oil field services bottlenecks, cost inflation and ESG considerations are limiting the ability to respond to higher prices. Global upstream spending has been on the decline since 2014, leading to a halving of resource life since the 2014 peak. This will take several years to reverse.

Technology has been a minefield of stock disasters as investors debate both fundamental risks and the prices at which these businesses should be valued. Many were "stay at home" beneficiaries in 2020, and as the world recovers from Covid, the piper is being paid. The Fund benefitted through its underweight across a range of tech-related industries in the quarter.

The Fund is underweight the non-US economies. Within its US holdings, the Fund maintains a bias toward those with a higher percentage of domestic revenue. We are still cautious on China where lockdowns under its zero-Covid policy are disrupting economic activity and sowing unrest. Chinese economic growth was already at risk from its real estate bubble and shifts in global supply chains.

In sum, the themes across the portfolio have changed little since late 2021, with renewed emphasis upon businesses that can navigate margin pressures amid "slowing but not slow" growth. The key question: "How much will mid-cycle earnings leverage help businesses deal with cost pressures?"

What is your macro perspective heading into the second half of 2022?

It is our belief that the journey from inflation anxiety to inevitable recession will be prolonged and include many notable stages. Our assumption is that 2022 will be characterized by a broad trading range for the major US equity benchmarks rather than an outright bear market. Our positioning has therefore been tactical rather than outright defensive. It is premature for end-of-cycle positioning.

Calamos Phineus Long/Short Fund

The developed world economies will slow persistently into 2023, yet not as quickly as generally feared. It is still far too early for recession talk. How this slowdown is felt across various industries as shifts in spending emerge in a post-Covid world will be the primary determinant of performance outcomes.

While the war in Europe has created widespread dissonance, it should be viewed as the second and lesser of the two shocks that have buffeted investors in 2022. The more important shock has been the repricing of developed world debt led by the US Federal Reserve.

The Federal Reserve recognizes the dilemma that a weakened economy will not resolve the underlying disorder. Yet Chairman Powell must talk tough to avoid losing control of the bond market. Equally, the Fed must distance itself from being "zero bound" to rates to avoid the appearance of negligence. The Fed fears that its excessive expansionary policies of recent years could be judged as irresponsible.

Once short rates are north of 2% by autumn, the Fed will have the flexibility to retreat to a "wait and see" policy aka "the wishful soft landing" approach, which amounts to tolerating higher inflation over the medium term. At that point, we suspect the Fed will find reasons to suspend its anti-inflationary commitment, especially if financial stress becomes apparent.

The good news is that the underpinnings of this economic cycle are stronger than most realize. In our view, 2% to 3% short rates will not trigger end of cycle risk. Demand momentum leading up to the Putin shock was extraordinary as consumer behavior in the US and Europe began to normalize post Covid. Much of the Emerging world including Asia outside China will join this rebound through the second half.

Some have focused upon the momentary inversion of the 10-year to 2-year US Treasury yield curve as a recession forecast, but this fear is misplaced. The logic of long versus short rates implies the 10-year to 3-month, or the 2-year to 3-month yield curves are the relevant signals. Both point to continued expansion. The recession countdown does not begin until 3-month money is more expensive than 10-year money, which is unlikely until mid-2023.

Recession risk will be material in 2024 or 2025. This is partly due to the lagged impact of less monetary largesse and also because the corporate sector is losing two key ingredients of the wishful soft landing: a low cost of capital and low input prices.

Rising equity volatility in 2022 cannot be traced to the underlying fundamentals of economic growth or corporate profits. Instead, it relates to the growing role of inflation in activity, the heightened uncertainty that inflation poses for capital allocation, and the inevitability that financial assets must be priced differently.

Fortuitously, inflation in goods prices should ease for the remainder of 2022. This reflects the inevitable easing of supply constraints in a post-Covid world as the "stay at home" bubble keeps popping in areas like streaming services, used car prices and personal computers. Gasoline prices and freight prices appear to be peaking. Housing prices will ease as the spike in mortgage rates impacts borrowing and forces layoffs at mortgage finance companies.

Calamos Phineus Long/Short Fund

What are your closing thoughts for Fund shareholders?

The bear market in the equity derivatives of long duration actually began about one year ago. We view this phase as largely complete. Markets should soon enter a phase of consolidation that implies ongoing equity volatility, but not an outright bear market. The latter will emerge later in 2023 when reflationary pressures give way to deflation in economic output and profits.

This transition to consolidation will be signaled by the climax of energy and commodity prices, marking a plateau in the rise of long-term inflation expectations in bond markets. An attempted rally to new highs will be sustained when the Federal Reserve has moved short-term rates above the 2% level, probably by early autumn. Debt markets confirm our conclusion that US recession risk is not acute.

At the start of 2022, we outlined a trading range for the S&P 500 Index of 4200 to 5000. That range is probably still intact, in our view. We do not believe the lows of late March will be materially (>5%) pierced (4000 to 4200). Earnings have been resilient, though the next few weeks will be telling. The 2022 earnings estimates are higher today than on March 31 across every US benchmark led by energy, materials and consumer discretionary.

The core of this outlook is our view that profit growth is sustainable, levels of credit stress stay low and it still makes sense to own equites rather than bonds. The absence of alternatives will encourage many to buy the dips. The year ahead may be characterized by an uncomfortable volatility, yet a sort of "going nowhere" rather than a new bear market. The silver lining is that Main Street could do relatively well.

The debate is whether these healthy fundamentals have been largely incorporated in prices, leading to a multi-year period of low returns. The loss of quasi-price stability of the last quarter-century should restore a genuine term premium in developed bond markets, which feeds the pricing of all financial assets including equities.

We think our risk-adjusted approach in this new era of financial history is ideally suited for our clients' objectives. This transition to a quite different setting will be prolonged and include many different stages. In the wake of excessively low interest rates for too long, this new era will seem synonymous with instability.

Calamos Phineus Long/Short Fund

ANNUALIZED RETURN: SINCE INCEPTION (5/1/02) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 2.36%, Class C shares is 3.11% and Class I shares is 2.11%. 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 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

Leveraging more than four decades of experience in convertibles, the Fund invests primarily in convertible securities of US and foreign companies without regard to market cap.

KEY FEATURES

^◼  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 six months ended April 30, 2022 ("semiannual period"), Calamos Convertible Fund had a returned -15.44% (Class I shares at net asset value) in line with the ICE BofA All US Convertibles Index (VXA0) return of -15.19%. For the same period, the S&P 500 Index returned -9.65%.

Since Class I shares inception on June 25, 1997, the Fund returned 8.32% on an annualized basis in line with an annualized gain of 8.40% for the ICE BofA All US Convertibles Index and an 8.40% annualized return for the S&P 500 Index.

What factors influenced performance during the semiannual period?

The convertible and equity markets were challenged during the reporting period by Covid-19 variants, supply chain disruptions, Russia's invasion of Ukraine, surging inflation, elevated oil prices and rising interest rates. Against this volatile backdrop, the US Convertible market represented by the ICE BofA All US Convertibles Index declined -15.19% and lagged behind the S&P 500 Index (-9.65%).

The convertible market is well represented by small and mid-sized growth issuers, and the semiannual period was especially challenging for these companies as evidenced by the -25.96% decline of the Russell 2500 Growth Index. As the underlying stocks of the convertible market declined -28.18%, convertibles provided downside mitigation by participating in only 54% of the drawdown of their underlying stocks. The equity market decline also meant that convertibles moved closer to their bond floor. With more than half of the convertible market priced below par at the end of April, convertibles held up better during the month of April; the ICE BofA All US Convertibles Index declined -7.10%, while the S&P 500 Index declined -8.72%.

From an economic sector perspective, the Fund benefited from its underweight and selection in the real estate sector as well as its favorable selection in the materials sector. In real estate, the Fund's names in the real estate services industry held up better than index holdings. In materials, the Fund's heavier position in the relatively strong performing diversified metals & mining industry added value. Conversely, the Fund's underweight in utilities and detrimental selection in the health care sector detracted from the period result. In health care, the Fund's holdings in the life sciences tools & services and health care technology industries lagged.

With the heightened market volatility, our preference has been convertibles with balanced risk/reward attributes, while maintaining an underweight to the most equity-sensitive convertibles, which generally lack favorable downside resilience. This equity-sensitive underweight position was supportive to the period return, as these issues underperformed the rest of the convertible market (-18.6% as measured by the ICE BofA Equity Alternative US Convertibles Index).

How is the Fund positioned?

We continue to emphasize the Fund's risk/reward trade-off and favor the balanced portion of the convertible market where the structural asymmetric profile offers

Calamos Convertible Fund

more potential upside participation than downside. We are underweight and selective within the most equity-sensitive portion of the market where convertible structures lack material downside risk mitigation. Given recent market volatility, the portion of the convertible market with lower equity sensitivity has increased. We are seeing some attractive opportunities within this segment to invest in potential market-leading companies without taking on full equity downside risk.

On a sector basis, technology represents the largest overall allocation in the Fund, given the sector's innovative companies and attractive risk-managed convertible structures. The largest relative overweight is consumer discretionary where we believe the strength of consumer demand for services will drive returns. The largest underweight is the financials sector where the convertible structures largely reflect elevated exposure to rising interest rate risk.

What are your closing thoughts for Fund shareholders?

The equity and credit markets have been knocked about by the turbulence of rising inflation and interest rates as well as intense geopolitical risks. Convertibles have not been immune to this increase in volatility, which also subdued the pace of new convertible issuance. While we have anticipated a deceleration in the annual volume of new convertibles after back-to-back years of near-record amounts, issuance thus far in 2022 has slowed to a crawl because of the heightened global uncertainty. However, we continue to expect that an eventual calming in the overall markets should return volumes back to a more traditional seasonal pace for the balance of the year. Despite the recent issuance slowdown, the strong issuance from 2020 and 2021 expanded the market and pushed back the maturity wall in the existing convertible market, which provides attractive opportunities in our view.

While macro risks have increased and the markets continue to adjust to a tightening monetary policy, history has shown that periods of short-term volatility can lead to longer-term opportunities. The recent pullback in the underlying stocks of convertible issuers has resulted in the equity sensitivity of the overall convertible market migrating toward the lower end of the post Covid-era range. Convertibles have also moved closer to their bond values as evidenced by the fact that more than half of the convertible market traded below par at the end of April. As we have seen over prior market cycles, actively managing the changing dynamics of convertibles through volatile times is a decided advantage we can offer to mitigate equity declines while still retaining upside equity optionality.

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

ANNUALIZED RETURN: SINCE INCEPTION (6/25/97) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.08%, Class C shares is 1.83% and Class I shares is 0.83%. 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.

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.

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

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

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

The Fund's portfolio of convertible securities can participate in upside equity movements with potentially limited downside exposure, providing 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 six months ended April 30, 2022 ("semiannual period"), Calamos Global Convertible Fund returned -16.78% (Class I shares at net asset value) in line with the Refinitiv Global Convertible Bond Index return of -16.33%.

Since Class I shares inception on December 31, 2014, the Fund returned 6.30% on an annualized basis in line with an annualized gain of 5.87% for the Refinitiv Global Convertible Bond Index.

What factors influenced performance during the semiannual period?

The global convertible and equity markets were challenged during the reporting period by Covid-19 variants, supply chain disruptions, the war in Ukraine, inflation, elevated oil prices and rising interest rates. Against this volatile backdrop, the global convertible market, represented by the Refinitiv Global Convertible Bond Index, declined -16.33% and lagged behind the MSCI World Index (-11.11%).

Small and mid cap growth issuers are well represented in the global convertible market, and the reporting period was especially challenging for convertibles issued by these smaller companies. The underlying stocks of the Refinitiv Global Convertible Bond Index were down -27.43% on average and resembled the return of the Russell Midcap Growth Index (-25.96%). Despite underperforming the MSCI World Index, convertibles demonstrated their ability to mitigate downside risk by participating in only 63% of their underlying stocks' drawdown. As the equity market moved lower, convertibles moved closer to their bond floor and their downside resilience further improved. At the end of April, more than half of the global convertible market was priced below par. In the month of April, as the MSCI World Index declined -8.27%, the Refinitiv Global Convertible Bond Index declined -6.57%.

Interest rates rose during the period as witnessed by the Bloomberg US Aggregate Bond Index yield to maturity increasing 127 basis points to 2.57%. Additionally, global high yield corporate credit spreads widened 44 basis points to 423 basis points according to Bloomberg. Rising interest rates and widening credit spreads impeded the bond component of convertibles during the reporting period.

From an economic sector attribution perspective, the Fund especially benefited from security selection in the consumer discretionary sector where holdings in the internet & direct marketing retail and hotels, resorts & cruise lines industries held up better than their index peers. Favorable security selection in the communication services sector also added value, as holdings in the interactive media & services industry outperformed. Areas that detracted the most from performance included materials and information technology. Within materials, an underweight allocation and security selection, notably in the specialty chemical industry, held back the relative return. In information technology, the relative return was hindered by security selection within the systems software, application software and data processing & outsourced services industries.

From a geographic perspective, the Fund benefitted from favorable selection in Emerging Europe & South Africa and Emerging Latin America, whereas security selection within Europe and Japan held back the relative result.

Calamos Global Convertible Fund

How is the Fund positioned?

With the uncertainty regarding both the Fed's success in engineering a soft landing and the outcome of the war in Ukraine, we have focused on maintaining an attractive risk/reward profile in the portfolio. As the equity market pulled back over the reporting period, the global convertible market saw a larger portion of convertibles trading closer to their bond floor. Because we have increased our allocation to balanced convertibles offering more attractive risk/reward characteristics, the Fund remains slightly more defensive than the convertible market from an equity-sensitivity perspective.

From a sector perspective, information technology, consumer discretionary and communication services comprise the largest allocations on an absolute basis, whereas energy, materials and consumer staples constitute the lightest absolute exposures. On a relative-to-benchmark basis, the largest overweight positions reside in information technology, real estate, and communication services. Conversely, industrials, materials and utilities make up the largest relative underweights.

From a regional perspective on an absolute basis, the portfolio has its heaviest allocations in the United States and Europe and lightest allocations in Canada and Emerging Europe and South Africa. On a relative basis, the portfolio holds overweight positions in Emerging Europe & South Africa, Emerging Asia and Japan. The portfolio is relatively underweight to Europe. In the past, the underweight to Europe was mainly driven by bottom-up convertible opportunities. However, the war in Ukraine along with inflation and a possible recession in Europe have added macro considerations to this underweight positioning.

What are your closing thoughts for Fund shareholders?

Rising inflation, war in Europe, and perceptions of the Fed being behind the curve made for a difficult reporting period. While we hope for a quick resolution to the war, deciphering what will happen with the Fed may take more time. We are skeptical that the Fed will need to raise rates past 1.0% – 1.5% to slow an economy that appears to have been slowing on its own—even before the spike in energy costs that is expected to brake the economy further. While we do not expect the Fed to overcorrect and trigger a recession in the US, we remain vigilant for signs of a policy error.

After two years of near records, global convertible issuance is off to a slow start in 2022 with $8.6 billion in new convertibles brought to market. This slowing of issuance tends to happen in times of a market dislocation, and the ambivalence wrought by the Fed's moves and the war in eastern Europe has made for a difficult environment for companies trying to raise equity and equity-linked capital. We expect that the primary market will reopen and, once it does, we expect to see a burst of new convertibles issued as has occurred during past similar periods.

We believe that convertibles provide an attractive way for an investor to take some risk off the table while staying invested in the equity market. The recent pullback in the underlying stocks of convertible issuers has resulted in the overall convertible market's equity sensitivity migrating toward the lower end of the post-Covid-era range. Convertibles have also moved closer to their bond values as evidenced by the fact that more than half of the convertible market traded below par at the end of April. While we view convertibles to be strategic allocations that should be held over full market, economic and interest rate cycles, the pullback and volatility in the market because of rising rates may provide tactical opportunities

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

in addition to strategic ones. For many investors, it's tough to buy equities in this elevated-volatility environment, and convertibles are a way to have equity exposure with less equity-market sensitivity.

GROWTH OF $1,000,000: SINCE INCEPTION (12/31/14) THROUGH 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.25%, Class C shares is 2.00% and Class I shares is 1.00%. 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 includes the effects of an expense reimbursement that improved results. 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.

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 Bloomberg US Aggregate Bond Index is a broad-based benchmark that measures the investment-grade, US dollar-denominated, fixed-rate taxable bond market of SEC-registered securities. The index includes bonds from the Treasury, Government-Related, Corporate, MBS (agency fixed-rate and hybrid ARM pass-throughs), ABS, and CMBS sectors.

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 six months ended April 30, 2022 ("semiannual period"), Calamos Timpani Small Cap Growth Fund posted a return of -35.32% (Class I Shares at net asset value) while the Russell 2000 Growth Index dropped -26.77%.

Since Class I shares inception on March 23, 2011, the Fund has returned 11.54% on an annualized basis, while the Russell 2000 Growth Index returned 8.84% 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 semiannual period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plan to tighten financial conditions (through a combination of interest rate hikes and a reduction of its balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 Index during Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022. Looking ahead, however, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Small cap growth stocks, which had enjoyed a strong recovery from their post-Covid lows, began to trend largely sideways through much of calendar year 2021, but then sustained a noticeable sell-off in November 2021 as this reporting period began. The market took a much more cautious stance on growth stocks within the small cap space as concerns around tightening financial conditions came to the fore. Valuations on small cap stocks dropped, even with strong earnings and revenues in the space, as investors acted on their worries.

Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the Russell 2000 Value Index decreasing -9.50%, while the Russell 2000 Growth Index declined -26.77%. Investors were clearly more sensitive to valuations and the prospect of reduced growth expectations associated with growth companies as well as names that had strongly outperformed the rest of the market from the lows in March 2020 through late 2021. During the semiannual period, the Russell 2000 Growth Index was led by sectors that would not be considered exceptionally growthy such as energy (+15.0%)—the only sector with positive performance—then consumer staples (-9.6%), materials (-12.0%), industrials (-17.7%), real estate (-19.2%) and utilities (-21.4%). Rounding out the sectors within the index were consumer discretionary (-26.7%), financials (-27.1%), information technology (-27.4%), communication services (-35.4%) and health care (-38.3%).

OVERVIEW

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

KEY FEATURES

^◼  Combines fundamental research with the analysis of market estimates to identify the underestimated growth differential

^◼  Analyzes secular trends to uncover exploitable investments 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.

The Fund's performance was positively affected by sector allocation decisions. The portfolio started the period with an overweight to the energy sector and further increased it over the course of the six months. As energy was the top-performing sector for the period, the overweight was strongly positive. Our view that the long period of underinvestment in energy businesses could create strong demand for equipment & services companies as well as drillers paid off. The portfolio's underweight to the lackluster health care sector was also additive to relative performance.

Security selection was a significant detractor from relative performance for the period. Market sentiment toward high growth businesses changed dramatically over the semiannual reporting period. Companies that had previously seen strong relative outperformance largely due to robust growth were punished significantly during this period. Often these businesses were able to deliver strong earnings and revenues during their quarterly announcements over the course of the period, but the market grew skeptical about the prospects for higher growth businesses going forward. Security selection within information technology, health care and industrials detracted from performance relative to the Russell 2000 Growth Index, though selection within financials was strongly additive. The market assigned a massive and negative re-rating to growth businesses across equity markets but especially beat down the small cap growth space. Broadly speaking, small cap growth companies that delivered strong quarterly earnings announcements saw their stock prices tumble, and those that did not deliver or gave cautious outlooks were discounted even more.

How is the Fund positioned?

We have been active in our efforts to manage risks during this time of heightened concerns about inflation and growth rates. Over the course of the reporting period, the Fund has sought to reduce investments in names with loftier valuations and greater variability of earnings. That said, the Fund continues to own a diversified portfolio of small cap growth businesses that we believe offer the best fundamental momentum available. Within information technology, for example, the Fund has reduced investment in more cyclically oriented areas, such as semiconductors, and has increased allocations to more reasonably priced productivity enhancers such as software. The Fund's increased investment in energy and reduction in industrials represented the most significant changes from a sector-weight standpoint. As mentioned previously, the energy sector had long been ignored, and we were able to uncover businesses where market expectations were too low in our view. In the industrials sector, we eliminated positions in areas where pricing was extreme because of the run-up during the post-Covid recovery; trucking comes to mind. We also reduced names that we continue to favor, though their valuations appear a bit rich.

What closing thoughts do you have for Fund shareholders?

While market pullbacks and corrections are a normal course of events this most recent sell-off at the market level and the targeting of small cap growth names particularly has been sharp and sudden. Clearly market participants are taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to be more cautious than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism. As the broad market wrestles

Calamos Timpani Small Cap Growth Fund

with the question of corrections versus bear markets, small cap stocks have already seen their bear market. This could be helpful going forward as small cap stocks and more so small cap growth stocks have already seen a more significant re-rating of the valuations that the market is willing to pay for future growth.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, indicating the overall health of the economy ex-inflation. Interest rate hikes increase the cost of capital, but in many cases corporations and individuals have locked in borrowing costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. That said, there are certainly parts of the economy that are more interest rate sensitive such as housing, and there are corporations that will need to access capital markets for funding, which we need to keep an eye on. The list of market worries is still quite long with concerns around interest rates, inflation, war in Ukraine, Covid variants, supply chains, and commodity prices as mentioned previously. But it's also important to keep a long-term perspective and investigate short-term opportunities created by market dislocations. As the economy slows from rampant growth to more traditional or low, albeit positive growth, businesses that can demonstrate the ability to grow should return to favor. If market valuations remain under pressure due to investor caution, earnings should then be the significant contributor to returns.

ANNUALIZED RETURN: SINCE INCEPTION (3/23/11) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.37%, Class C shares is 2.11%, Class I shares is 1.11% and Class R6 shares is 1.02%. 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 and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

Calamos Timpani Small Cap Growth Fund

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.

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

The Russell 2000^® Value Index measures the performance of the small-cap value segment of the US equity universe. It includes those Russell 2000 companies with relatively lower price-to-book ratios, lower forecasted medium term (2 year) growth and lower sales per share historical growth (5 years).

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

OVERVIEW

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

KEY FEATURES

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

^◼  Pursues active management in a less followed investment space.

^◼  Analyzes secular trends to uncover exploitable investment opportunities specific to small and mid cap companies.

PORTFOLIO FIT

Investing in small and mid cap companies is an important component of a diversified investment strategy. Small and midsize companies tend to have a greater chance of growing rapidly and outperforming large cap companies, yet this greater potential also raises the probability of greater volatility—which is why we believe active management is crucial.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS TIMPANI SMID GROWTH FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the six months ended April 30, 2022 ("semiannual period"), Calamos Timpani SMID Growth Fund returned -33.87% (Class I Shares at net asset value), while the Russell 2500 Growth Index delivered a -25.96% return.

What factors influenced performance during the semiannual period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plan to tighten financial conditions (through a combination of interest rate hikes and a reduction of its balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 Index for Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022. Looking ahead, however, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Small-to-mid cap growth stocks, which had enjoyed a strong recovery from their post-Covid lows, began to trend largely sideways through much of calendar year 2021, but then sustained a noticeable sell-off in November 2021 as this reporting period began. The market took a much more cautious stance on growth stocks within the small cap space as concerns around tightening financial conditions came to the fore. Valuations on small cap stocks dropped, even with strong earnings and revenues in the space as investors acted on their worries.

Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the Russell 2500 Value Index decreasing -6.76%, while the Russell 2500 Growth Index declined -25.96%. Investors were clearly more sensitive to valuations and the prospect of reduced growth expectations associated with growth companies as well as names that had strongly outperformed the rest of the market from the lows in March 2020 through late 2021. During the semiannual period, the Russell 2500 Growth Index was led by sectors that would not be considered exceptionally growthy such as energy (+16.3%)—the only sector with positive performance. Materials (-12.0%), real estate (-11.6%), utilities (-14.9%) and consumer staples (-16.0%) also led. Rounding out the sectors within the growth index were industrials (-21.0%), financials (-24.6%), information technology (-25.5%), consumer discretionary (-25.8%), communication services (-35.1%) and health care (-37.6%).

The Fund's performance was positively affected by sector allocation decisions. The portfolio started the period with an overweight to the energy sector and further increased it over the course of the six months. As energy was the top-performing sector for the period, the overweight was strongly positive. Our view that the long period of underinvestment in energy businesses could create strong demand for equipment & services companies as well as drillers paid off. The portfolio's underweight to the lackluster health care sector was also additive to relative performance.

Calamos Timpani SMID Growth Fund

Security selection was a significant detractor from relative performance for the period. Market sentiment toward high growth businesses changed dramatically over the semiannual reporting period. Companies that had previously seen strong relative outperformance largely due to robust growth were punished significantly during this period. Often, these businesses were able to deliver strong earnings and/or revenues during their quarterly announcements over the course of the period, but the market grew skeptical about the prospects for higher growth businesses going forward. Security selection within information technology, industrials and health care detracted from performance relative to the Russell 2500 Growth Index, though selection within financials was strongly additive. The market assigned a massive and negative re-rating to growth businesses across equity markets but especially beat down the small-to-mid cap growth space. Broadly speaking, smaller cap growth companies that delivered strong quarterly earnings announcements saw their stock prices tumble, and those that did not deliver or gave cautious outlooks were discounted even more.

How is the Fund positioned?

We have been active in our efforts to manage risks during this time of heightened concerns about inflation and growth rates. Over the course of the reporting period, the Fund has sought to reduce investments in names with loftier valuations and greater variability of earnings. That said, the Fund continues to own a diversified portfolio of small cap growth businesses that we believe offer the best fundamental momentum available. Within information technology, for example, the Fund has reduced investment in more cyclically oriented areas, such as semiconductors, and has increased allocations to more reasonably priced productivity enhancers such as software. The Fund's increased investment in the energy sector and reduction among industrials represented the most significant changes from a sector weight standpoint. As mentioned previously, the energy sector had long been ignored and we were able to uncover businesses where market expectations were too low in our view. In the industrials sector we eliminated positions in areas where pricing was extreme because of the run-up during the post-Covid recovery; trucking comes to mind. We also reduced names that we continue to favor, though their valuations appear a bit rich.

What closing thoughts do you have for Fund shareholders?

While market pullbacks and corrections are a normal course of events, this most recent sell-off at the market level and the targeting of small cap growth names particularly has been sharp and sudden. Clearly market participants are taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to be more cautious than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism. As the broad market wrestles with the question of corrections versus bear markets, smaller cap stocks have already seen their bear market. This could be helpful going forward as small-to-mid cap stocks and more so small-to-mid cap growth stocks have already seen a more significant re-rating of the valuations that the market is willing to pay for future growth.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, validating the overall health of the economy ex-inflation. Interest rate hikes increase the cost of capital, but in many cases corporations and individuals have locked in borrowing

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 Timpani SMID Growth Fund

costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. That said, there are certainly parts of the economy that are more interest rate sensitive such as housing, and there are corporations that will need to access capital markets for funding, which we need to keep an eye on. The list of market worries is still quite long with concerns spanning interest rates, inflation, war in Ukraine, Covid variants, supply chains, and commodity prices as mentioned previously. But It's also important to keep a long-term perspective and investigate short-term opportunities created by market dislocations. As the economy slows from rampant growth to more traditional or low, albeit positive growth, businesses that can demonstrate the ability to grow should return to favor. If market valuations remain under pressure due to investor caution, earnings should then be the significant contributor to returns.

GROWTH OF $1,000,000: SINCE INCEPTION (7/31/19) THROUGH 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.79%, Class I shares is 1.55% and Class R6 shares is 1.48%. 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

Calamos Timpani SMID Growth Fund

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.

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

The Russell 2500(TM) Value Index measures the performance of the small to mid-cap value segment of the US equity universe. It includes those Russell 2500 companies with relatively lower price-to-book ratios, lower forecasted medium term (2 year) growth and lower sales per share historical growth (5 years).

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

^◼  Seeks to provide attractive returns through an emphasis on higher-growth US companies spanning the full range of market capitalizations and sectors.

^◼  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.

^◼  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 six months ended April 30, 2022 ("semiannual period"), Calamos Growth Fund returned -22.02% (Class I Shares at net asset value) versus the S&P 1500 Growth Index return of -16.74%. By way of comparison, the broad equity market, as measured by the S&P 500 Index, also declined with a return of -9.65% for the same period.

Since Class I shares inception on September 18, 1997, the Fund has returned 11.09% on an annualized basis. The S&P 1500 Growth Index, the primary benchmark, returned 8.78% over the same period, and the S&P 500 Index returned 8.17%. We believe these comparisons demonstrate the Fund's ability to outdistance the growth and broad indices over full market cycles.

What factors influenced performance during the semiannual period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plans to tighten financial conditions (through a combination of interest rate hikes and a reduction of the Fed's balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 for Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022 as well. Looking forward, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the S&P 1500 Value Index decreasing only -1.94%, while the S&P 1500 Growth Index declined -16.74%. Investors were clearly more sensitive to valuation and the prospect of reduced growth expectations associated with growth companies as well as names that had strongly outperformed the rest of the market from the lows of March 2020 through late 2021. The S&P 1500 Growth Index was led by sectors that would not be considered exceptionally growthy such as energy (+24.8%), consumer staples (+3.2%), materials (+0.2%), real estate (-2.2%), and utilities (-4.6%). Rounding out the sectors within the growth index were healthcare (-13.1%), industrials (-14.0%), information technology (-14.0%), financials (-18.7%), consumer discretionary (-22.8%) and communication services (-32.4%).

The Fund's sector allocation had a largely neutral impact on relative performance. An overweight to the industrials sector was additive, yet an underweight to the relatively small real estate sector was significantly detrimental as real estate names strongly outperformed the growth index. Individual issue selection was a relative drag on performance, as companies with higher growth estimates came more into doubt amongst the investment community. Within information technology, holdings in technology hardware, storage & peripherals as well as Internet services & infrastructure lagged during the period. Communication services names

Calamos Growth Fund

also trailed those of the market in areas such as interactive media and movies & entertainment. On a positive note, selection within financials and consumer discretionary were additive to relative performance during the period.

How is the Fund positioned?

While a decidedly more defensive tone has permeated the market recently, US equity markets have been highly rotational with fits and starts of leadership from a variety of sectors and factors. As such, the Fund remains broadly diversified. The Fund continues to own secular growth opportunities that should be more enduring such as productivity-enhancing services. Additionally, the Fund maintains investments in consumer-related cyclical areas, as consumer balance sheets are still strong and services spending shows opportunities for improvement. The Fund also has sought to manage risk around the higher growth, but perhaps more speculative opportunities by reducing risk where valuations are stretched relative to the broad market. As of the end of the reporting period, the Fund held overweights to industrials, consumer discretionary, health care and consumer staples. During the period, the Fund further increased its underweight to information technology and also migrated its financials allocation to an underweight.

What closing thoughts do you have for Fund shareholders?

While market pullbacks and corrections are a normal course of events this most recent sell-off at the market level and targeting growth names particularly has been sharp and sudden. Market participants are taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to be more cautious than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism on that front.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, validating the overall health of the economy ex-inflation. Interest rate hikes increase the cost of capital, but in many cases corporations and individuals have locked in borrowing costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. That said, there are certainly parts of the economy that are more interest-rate sensitive such as housing, and there are corporations that will need to access capital markets for funding, which we need to keep an eye on. The list of market worries is still quite long and includes concerns about interest rates, inflation, the war in Ukraine, Covid variants, supply chains and commodity prices as mentioned previously. But it's also important to keep a long-term perspective and investigate short-term opportunities created by market dislocations. As the economy slows from rampant growth to more traditional or low, albeit positive growth, businesses that can demonstrate the ability to grow should return to favor.

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 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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.

Performance results do not include adjustments made for financial reporting purposes in accordance with US generally accepted accounting principles and may differ from amounts reported in the financial highlights.

As of the prospectus dated 3/1/22, the Fund's gross expense ratio for Class A shares is 1.28%, Class C shares is 2.04% and Class I shares is 1.03%. 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.

The S&P 1500 Value Index consists of the value 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.

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 equities, convertibles, fixed income securities and options, endeavoring to balance risk/reward while providing growth and income.

KEY FEATURES

^◼  Leverages more than four decades of experience combining equities, convertibles, fixed income securities and options to provide equity-like participation while maintaining a lower risk posture throughout the market cycle.

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

^◼  Has consistently paid a competitive distribution since inception.

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 six months ended April 30, 2022 ("semiannual period"), Calamos Growth and Income Fund posted a return of -10.56% (Class I Shares at net asset value) versus a return of -9.65% for the S&P 500 Index. The ICE BofA All US Convertibles ex Mandatory Index registered a decline of -16.32% for the period. We manage this Fund with the goal of achieving upside equity participation and potential downside risk mitigation over full market cycles. Since its Class I shares inception on September 18, 1997, the Fund has returned 9.84% on an annualized basis versus an 8.17% gain for the S&P 500 Index and 8.50% 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 byproduct 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 0.76 (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 semiannual period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plan to tighten financial conditions (through a combination of interest rate hikes and a reduction of its balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 for Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022. Looking ahead, however, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to endemic, lockdowns in China still threaten the course of more normal economic activity globally.

There wasn't much that worked well for investment markets over the reporting period. The more typical safety of high-quality bonds proved elusive as the Bloomberg US Aggregate Bond Index saw a big decline of -9.47% for the period. Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the S&P 500 Value Index decreasing only -1.64%, while the S&P 500 Growth Index declined -16.86%. Investors were more sensitive to valuation and the prospect of reduced growth expectations associated with growth

Calamos Growth and Income Fund

companies as well as names that had strongly outperformed the rest of the market from the lows of March 2020 through late 2021. The S&P 500 Index was led by commodity and defensive oriented sectors that would not be considered exceptionally growthy such as energy (+34.5%), consumer staples (+10.7%), utilities (+8.2%), materials (+0.8%), and real estate (-1.0%). Rounding out the index sectors were healthcare (-1.8%), industrials (-8.2%), information technology (-12.6%), financials (-13.5%), consumer discretionary (-18.9%), and communication services (-27.5%).

For the semiannual period, the Fund slightly lagged the all-equity index largely due to issue selection and an uncharacteristically difficult stretch for convertible bonds relative to the broad equity market. Sector allocations were modestly additive to relative performance partially due to the funds slight overweight to the energy sector, which led the equity markets overall. Conversely, an underweight to health care was a slight distraction from sector positioning. In terms of security selection, portfolio holdings within the financials sector lagged those of the S&P 500 Index as did holdings within the consumer discretionary sector. Within financials, relative performance lagged more because of what the Fund didn't own in multi-sector holdings, rather than struggles from companies the Fund held. As for health care, convertible securities in health care technology and health care services lagged the equity names within the S&P 500 Index. In our view, convertible securities traditionally offer more risk-managed access to higher growth businesses. But in this reporting period, the underlying equities of higher growth, small and mid cap businesses were significantly out of favor as investors contemplated growth potential in light of the Fed's goals to slow down economic activity and inflation. Security selection was additive within communication services and industrials where convertible securities in movies & entertainment and airlines were significantly additive.

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. Traditional fixed income continues to face pressure in a rising interest rate environment. Overall, we are emphasizing companies with higher quality characteristics, such as balance sheet strength, earnings quality, and stable cash flow generation, among other factors. Thematically, we are seeking companies positioned to benefit from a goods-to-services transition, where demand is improving not decelerating. Our positioning is likely to become more positive/constructive once the investment markets move beyond this period of rebasing expectations and stabilize.

What closing thoughts do you have for Fund shareholders?

Our base case is that the US economy has entered a slowing mid-cycle period. The Fed's mission to slow economic growth in order to stem the tide of rampant inflation has complicated the economic cycle. While the Fed wishes to curb inflation, the economy was already slowing down, in our view. The end of massive stimulus, the war in Ukraine and global sanctions, Covid lockdowns in China, and continuing supply chain issues have all served to slow economic activity.

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

While market pullbacks and corrections are a normal course of events, this most recent sell-off at the market level and in growth names particularly has been sharp and sudden. Clearly market participants are taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to be more cautious than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, validating the overall health of the economy ex inflation. Interest rate hikes increase the cost of capital, but in many cases corporations and individuals have locked in borrowing costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. That said, there are certainly parts of the economy that are more interest-rate sensitive such as housing, and there are corporations that will continue to need to access capital markets for funding that will be worth keeping an eye on. The list of market worries is still quite long and includes concerns about interest rates, inflation, the war in Ukraine, waves of Covid, supply chains, commodity prices as mentioned previously, but It's also important to keep a long-term perspective and investigate short term opportunities created by market dislocations. A risk-conscious approach to equity markets appears appropriate in light of these conditions.

ANNUALIZED RETURN: SINCE INCEPTION (9/18/97) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.06%, Class C shares is 1.81%, Class I shares is 0.81% and Class R6 shares is 0.73%. 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.

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

The S&P 500 Growth Index, representing the fastest growing companies in the S&P 500, measures growth stocks using three factors: sales growth, the ratio of earnings change to price, and momentum.

The S&P 500 Value Index measures value stocks using three factors: the ratios of book value, earnings, and sales to price. Constituents are drawn from the S&P 500.

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 an 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 six months ended April 30, 2022 ("semiannual period"), Calamos Dividend Growth Fund returned -9.87% (Class I shares at net asset value), largely in line with the S&P 500 Index return of -9.65%.

What factors influenced performance during the semiannual period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plan to tighten financial conditions (through a combination of interest rate hikes as well as a reduction of the Fed's balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 for Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022 as well. Looking forward, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to endemic, lockdowns in China still threaten the course of more normal economic activity globally.

Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the S&P 500 Value Index decreasing only -1.64%, while the S&P 500 Growth Index declined -16.86%. Investors were clearly more sensitive to valuation and the prospect of reduced growth expectations associated with growth companies as well as names that had strongly outperformed the rest of the market from the lows of March 2020 through late 2021. For the semiannual period, the S&P 500 Index was led by commodity and defensive-oriented sectors that would not be considered exceptionally growthy such as energy (+34.5%), consumer staples (+10.7%), utilities (+8.2%), materials (+0.8%), and real estate (-1.0%). Rounding out the sectors within the index were healthcare (-1.8%), industrials (-8.2%), information technology (-12.6%), financials (-13.5%), consumer discretionary (-18.9%), and communication services (-27.5%).

The Fund's sector allocation was marginally additive to relative performance for the reporting period. An overweight to energy, which was the market's leading sector, added value as did our underweight to communication services where we had concerns about the sector's valuations. That said, an underweight to the real estate sector, although a small percentage of the S&P 500 Index, was a drag on relative performance.

While the Fund did reduce weightings in some of the more speculative growth businesses trading at loftier valuations and does own stocks within the value arena, the portfolio has an overall slight bias toward growth businesses—looking to that growth to assist in dividends and dividend growth. For the reporting period, security selection, notably in financials and consumer discretionary, was a slight drag on relative performance. In financials, an emphasis on investment banking & brokerage as well as diversified banks was detrimental as those industries underperformed. Within consumer discretionary, names within auto parts as well as hotels, resorts & cruise lines struggled. Strong stock selection in health care was noteworthy as well as information technology. Within health care,

Calamos Dividend Growth Fund

the portfolio's names in pharmaceuticals and health care equipment strongly outperformed those of the market. Within information technology, Fund holdings in environmental facilities & services as well as railroads boosted results.

How is the Fund positioned?

The Fund is broadly diversified by sector, favoring individual stock selection to significant sector over and underweights. The Fund's largest underweight is in the real estate sector, which has more fulsome valuations relative to growth opportunities, in our view. The most significant changes in relative weightings were reductions to information technology and financials. The largest increases to relative sector weights occurred within health care names and consumer staples. While consumer staples can be considered more defensive, our additions to the space are tied to consumer strength. The Fund's mix of common stocks includes cyclical and secular growth opportunities, though the greater focus is on names that offer higher quality consistent earnings, strong cash flow and growth potential.

What closing thoughts do you have for Fund shareholders?

Our base case is that the US economy has entered a slowing mid-cycle period. The Fed's mission to slow economic growth in order to stem rampant inflation has complicated the economic cycle. While the Fed wishes to curb inflation, the economy was already slowing down, in our view. The end of massive stimulus, the war in Ukraine and global sanctions, Covid lockdowns in China, and continued supply chain issues have all served to slow economic activity.

While market pullbacks and corrections are a normal course of events this most recent sell-off at the market level and targeting of growth names particularly has been sharp and sudden. Market participants are clearly taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to proceed more cautiously than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism on that front.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, validating the overall health of the economy ex inflation. Interest rate hikes increase the cost of capital, but in many cases corporations and individuals have locked in borrowing costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. That said, there are certainly parts of the economy that are more interest-rate sensitive such as housing, and there are corporations that need to access capital markets for funding, which we need to keep an eye on. The list of market worries is still quite long and includes interest rates, inflation, the war in Ukraine, Covid variants, supply chains and commodity prices as mentioned previously. But It's also important to keep a long-term perspective and investigate short-term opportunities created by market dislocations. Our focus on stable companies that generate ample free cash flow appears appropriate in light of these conditions.

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 2.04%, Class C shares is 2.78% and Class I shares is 1.80%. 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.

The S&P 500 Growth Index, representing the fastest growing companies in the S&P 500, measures growth stocks using three factors: sales growth, the ratio of earnings change to price, and momentum.

The S&P 500 Value Index measures value stocks using three factors: the ratios of book value, earnings, and sales to price. Constituents are drawn from the S&P 500.

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 six months ended April 30, 2022 ("semiannual period"), Calamos Select Fund returned -11.96% (Class I shares at net asset value), while the S&P 500 Index returned -9.65%.

What factors influenced performance over the period?

The US equity market struggled over the semiannual period as soaring inflation and the Federal Reserve's plan to tighten financial conditions (through a combination of interest rate hikes and a reduction of its balance sheet) gave investors reasons to re-evaluate future economic growth and the prices paid for equities. That said, companies continued to report strong earnings and revenue growth during the period with 31% earnings growth for the S&P 500 for Q4 2021, and current indications point to strong, positive earnings growth for Q1 2022. Looking ahead, however, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, rising energy prices and the like. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Growth stocks lagged relative to value and defensive stocks during the period, as evidenced by the S&P 500 Value Index declining only -1.64%, while the S&P 500 Growth Index delivered a return of -16.86%. Investors were clearly more sensitive to valuations and the prospect of reduced growth expectations associated with growth companies as well as names that had strongly outperformed the rest of the market from the lows in March 2020 through late 2021. For the semiannual period, the S&P 500 Index was led by commodity and defensive oriented sectors that would not be considered exceptionally growthy such as energy (+34.5%), consumer staples (+10.7%), utilities (+8.2%), materials (+0.8%) and real estate (-1.0%). Rounding out the sectors within the index were healthcare (-1.8%), industrials (-8.2%), information technology (-12.6%), financials (-13.5%), consumer discretionary (-18.9%) and communication services (-27.5%).

The Fund's sector allocation was broadly neutral to relative performance for the reporting period. An overweight to consumer staples, which performed quite well in the more defensive environment, added value as did our underweight to information technology where we had concerns about valuations. That said, a lack of exposure to the real estate sector, although a small percentage of the S&P 500 Index, was a drag on relative performance.

While the Fund did reduce weightings in several more speculative growth businesses trading at loftier valuations, and we do own stocks within the value arena, the portfolio overall has a slight bias toward growth businesses. Security selection within information technology, consumer discretionary and utilities were all drags on relative performance. In information technology, the Fund did reduce its overall allocation and sought to reduce higher valued names, but the Fund did still own higher prospective growth businesses that are geared toward enhancing productivity. Those stocks, which had been strong performers previously and continue to offer higher growth opportunities, fell out of favor with the nervous market. Within consumer discretionary, names within footwear as well as auto

OVERVIEW

The Fund primarily invests in a concentrated portfolio of large cap US equities with broad representation across sectors, industries and investment styles.

KEY FEATURES

^◼  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 respective sectors.

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

^◼  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 on portfolio performance.

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.

parts struggled. In utilities, holdings within electric utilities lagged those of the overall sector. By way of contrast, strong stock selection was notable within health care and industrials. Within health care, the portfolio's selection in pharmaceuticals strongly outperformed those of the market and selection within managed care also added to relative performance. Within the industrials sector, Fund holdings in environmental facilities & services as well as railroads outperformed for the period.

How is the Fund positioned?

While a decidedly more defensive tone has permeated the market recently, US equity markets have been highly rotational with fits and starts of leadership from a variety of sectors and factors. As such, the Fund remains broadly diversified by sector. The real estate sector is the only space where the Fund has no allocation. During the reporting period, the Fund noticeably increased its allocations in health care as well as consumer staples. Health care names had struggled previously, offer attractive valuations and are not as dependent on rampant GDP growth. Consumer staples tend to offer more stability with the trade-off typically being less dynamic growth. The Fund's focus has been on more dynamic growth opportunities associated with those consumers who still indicate a propensity to spend. The most significant reductions from a sector allocation standpoint occurred within information technology and financials. As mentioned previously, information technology was reduced in an effort to manage risk around companies with the good and not-so-good characteristics of higher growth yet higher valuations. In hindsight a further reduction would have worked better during the reporting period, yet we still see opportunity for these dynamic, productivity enhancing businesses. In the financials space, changes were more geared at the company level, where the portfolio exited three positions while adding two new names, as opposed to strong top-down concerns.

The Fund continues to favor large cap names across the spectrum of secular growth opportunities that should be more enduring such as productivity enhancing services as well as consumer-related cyclical areas. Consumer balance sheets are still strong and services spending still shows opportunities for improvement. Nominal growth measures are still strong, validating the resilience of the US consumer, though we will keep a watchful eye on inflation and employment measures for indications of potential changes.

What closing thoughts do you have for Fund shareholders?

While market pullbacks and corrections are a normal course of events, this most recent sell-off at the market level and of growth names in particular has been sharp and sudden. Clearly market participants are taking a wait-and-see approach regarding the Fed's ability to slow down the economy in an effort to contain inflation. It's also important to remember that interest rate hikes have a delayed effect on the overall economy, and we believe the Fed may be able to be more cautious than what the market is currently pricing in terms of the tightening of financial conditions. We have already seen indications of slowing inflation data that gives us reason for optimism.

Overall, corporate balance sheets and personal balance sheets are still quite healthy. Nominal levels of economic activity have been strong, indicating the good overall health of the economy ex inflation. Interest rate hikes increase the cost of

Calamos Select Fund

capital, but in many cases corporations and individuals have locked in borrowing costs and should be less affected by these moves. Labor markets are strong, which is also a positive sign for the economy. Nevertheless, there are certainly parts of the economy that are more interest-rate sensitive such as housing, and there are corporations that will need to access capital markets for funding, which we will keep an eye on. The list of market worries is still quite long and includes concerns about interest rates, inflation, the war in Ukraine, Covid variants, supply chains, and commodity prices as mentioned previously, but It's also important to keep a long-term perspective and investigate short-term opportunities created by market dislocations.

ANNUALIZED RETURN: SINCE INCEPTION (3/1/02) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.57%, Class C shares is 2.33% and Class I shares is 1.32%. 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.

The S&P 500 Growth Index, representing the fastest growing companies in the S&P 500, measures growth stocks using three factors: sales growth, the ratio of earnings change to price, and momentum.

The S&P 500 Value Index measures value stocks using three factors: the ratios of book value, earnings, and sales to price. Constituents are drawn from the S&P 500.

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 six months ended April 30, 2022 ("semiannual period"), Calamos International Growth Fund returned -22.36% (Class I shares at net asset value) versus the -18.20% return for the MSCI EAFE Growth Index and -11.68% return for the MSCI ACWI ex USA Index. The Fund's return landed within the 63rd percentile of the Morningstar Foreign Large Growth category during this time period.*

Since Class I shares inception on March 17, 2005, the Fund has returned 7.57% on an annualized basis compared with a 5.94% return for the MSCI EAFE Growth Index and 5.40% increase for the MSCI ACWI ex USA Index. We believe this demonstrates the Fund's ability to generate long-term excess returns over complete market cycles.

What factors influenced performance during the semiannual period?

International stocks struggled in the semiannual period as markets traversed a landscape characterized by higher inflation, rising interest rates, and heightened geopolitical tension. Looking ahead, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, and high commodity prices. While Covid has largely transitioned from a pandemic to an endemic phase, the recent lockdowns in China still threaten the course of more normal economic activity globally.

The Fund trailed the index over the semiannual period due to lagging individual security selection. Our Fund holdings in foreign stocks with more cyclical and secular growth characteristics trailed the narrow, defensive market sectors and industries that held up relatively better amid the broad sell-off in international equities.

Positive Influences on Performance

Energy. The Fund's average overweight position and favorable security selection in energy helped buoy relative returns. Specifically, oil & gas exploration & production and integrated oil & gas supported return.

Materials. Leading security selection and an average overweight position in materials, notably in copper and diversified metals & mining, added to the Fund's performance.

Negative Influences on Performance

Information Technology. Over the period, security selection and an average overweight stance within the information technology sector hampered relative performance, as holdings in the internet services & infrastructure and semiconductor equipment industries underperformed.

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 markets.

KEY FEATURES

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

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

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

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 4/30/22. Morningstar category percentile ranking is based on annualized total return for the 1-year, 3-year, 5-year and 10-year periods. Calamos International Growth Fund Class I shares were in the 63rd, 2nd, 7th and 40th percentiles of 454, 392, 349 and 223 funds for the 1-year, 3-year, 5-year and 10-year periods, respectively, for the Morningstar Foreign Large Growth category.

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.

Communication Services. Security selection in communication services lost ground as well, especially in the interactive home entertainment and advertising industries.

Geographic Performance

Favorable security selection in EMEA added value to Fund performance. The lack of any exposure in Poland helped relative performance.

By contrast, security selection in Emerging Asia negatively impacted the Fund's performance. The Fund's securities fell short of benchmark constituents, especially those in China and Taiwan. Security selection in Europe also trailed the index and hampered returns in the period.

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, actively integrating them into the investment decision-making process.

^◼  The Fund is positioned with a combination of cyclical and secular growth opportunities, including commodities exposure, reopening/recovery stories, and select defensives.

^◼  Industrials, consumer discretionary, technology, health care, financials and materials represent the largest sector weights in the Fund. Key industry positions include pharmaceuticals, banks, semiconductors, aerospace and defense, metals & mining, and travel.

^◼  We own a range of energy and materials holdings in companies positioned to benefit from global supply-and-demand dynamics and attractive capital efficiency.

^◼  We have an underweight stance in more defensive areas including utilities, real estate, consumer staples and traditional telecoms.

^◼  Through a geographic lens, we own diversified holdings in Europe across a range of end markets and business models. The Fund is positioned in a blend of cyclical and secular growth companies, commodity exposures, along with select reopening and defensive areas.

^◼  We own positions in emerging markets within key demand areas such as semiconductors, branded apparel, interactive media, and higher-quality financials.

^◼  We hold a moderate weight in Japan, which includes several higher-quality companies with attractive business models positioned to benefit as global supply chains normalize in the coming months.

What closing thoughts do you have for Fund shareholders?

International equities continue to navigate a set of formidable crosscurrents. We are analyzing many aspects of economic activity, alongside geopolitical events, key policy actions and corporate earnings. Global monetary conditions are in a period of transition as multiple central banks tapered asset purchases and raised interest rates in recent months. We see opportunities in foreign stocks that may benefit from normalizing supply chains and inflation in the months ahead,

Calamos International Growth Fund

earnings growth potential, and a range of exploitable valuation differences across regions. Despite these tailwinds, we are mindful that markets will experience volatility and we remain closely attuned to risks.

In terms of Fund positioning, we favor investments in companies with near-term earnings growth potential, flexible balance sheets, supportive valuations, and advantaged business models. From a sector perspective, we see opportunities in technology, consumer discretionary, industrials, health care, energy, and materials with compelling fundamentals. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in international markets.

ANNUALIZED RETURN: SINCE INCEPTION (3/16/05) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.56%, Class C shares is 2.31%, Class I shares is 1.31% and Class R6 shares is 1.22%. 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).

Calamos International Growth Fund

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 USA Index represents the performance of large- and mid-cap stocks across developed and emerging markets excluding the United States. The MSCI ACWI ex USA 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.

The Morningstar Foreign Large Growth Category is comprised of funds that seek capital appreciation by investing in large international stocks that are growth-oriented. Large-cap foreign stocks have market capitalizations greater than $5 billion. Growth is defined based on high price/book and price/cash flow ratios, relative to the MSCI EAFE Index. These funds typically will have less than 20% of assets invested in US stocks.

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 Evolving World Growth Fund

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

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

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

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

PORTFOLIO FIT

With 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

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the six months ended April 30, 2022 ("semiannual period"), Calamos Evolving World Growth Fund returned -17.66% (Class I shares at net asset value) versus a -14.04% return for the MSCI Emerging Markets Index.

Since its Class I shares inception on August 15, 2008, the Fund has returned 5.39% on an annualized basis compared with the 3.39% return of the MSCI Emerging Markets Index. We believe this demonstrates the Fund's ability to access emerging market opportunities and deliver leading returns while pursuing a risk-managed investment approach over complete market cycles.

What factors influenced performance during the semiannual period?

Emerging markets struggled during the semiannual period against a backdrop of higher inflation, heightened geopolitical tension, and a stronger dollar. Looking ahead, investors and companies have lowered expectations given the risks presented by interest rates, the war in Ukraine, supply chain disruptions, and high commodity prices. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Pursuant to our objectives, the Evolving World Growth Fund navigated the volatile markets while employing an active blend of economic cohorts and drawing on a wide investment universe. The Fund's return trailed the index over the semiannual due primarily to lagging security selection. Our holdings in emerging market companies with cyclical and secular growth characteristics trailed the more narrow, defensive market sectors and industries that held up relatively better amid the correction in emerging markets.

Positive Influences on Performance

Energy. The Fund's leading security selection in energy outperformed. Names in integrated oil & gas and oil & gas equipment & services were leading contributors.

Materials. Favorable security selection in materials, notably in copper and aluminum, added to the Fund's performance.

Negative Influences on Performance

Communication Services. Over the period, security selection and an average overweight allocation within the communication services sector detracted from relative performance, as holdings in the interactive home entertainment and integrated telecommunication services industries lagged.

Financials. Selection in financials, specifically in the diversified banks and life & health insurance industries, lost ground on a relative basis.

Calamos Evolving World Growth Fund

Geographic Performance

Favorable security selection and an underweight stance in EMEA drove relative performance. Also, the Fund benefitted from select multinationals in the United States with significant revenue exposure in emerging markets.

In contrast, security selection in Emerging Asia dragged on return. Holdings in Taiwan and India hindered relative returns. Moreover, selection in Emerging Latin America underperformed. Specifically, our holdings in Brazil and Argentina trailed.

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, actively integrating them into the investment decision-making process.

^◼  We maintain a constructive view on opportunities in emerging markets. Our Fund positioning favors a blend of cyclical and secular growth companies, commodity exposures, reopening stories and select defensives.

^◼  From a sector perspective, the Fund's largest weights are in financials, technology, consumer discretionary, materials and energy. We own holdings within key demand areas including higher-quality financials, semiconductors, interactive media & services, internet retail, and metals & mining.

^◼  We own a range of energy and materials holdings in companies positioned to benefit from global supply-and-demand dynamics and attractive capital efficiency.

^◼  We hold a low weight or underweight in defensive sectors including utilities, health care, and traditional telecoms, reflecting our more favorable view of opportunities in the sectors noted above.

^◼  From a geographic perspective, we favor investments in India, China, Taiwan, Brazil, Mexico, South Africa, and an expanding set of opportunities in parts of Southeast Asia and the Middle East.

What closing thoughts do you have for Fund shareholders?

Emerging markets continue to navigate a set of complex crosscurrents. We are analyzing many aspects of economic activity, alongside the geopolitical backdrop, key policy actions and corporate earnings. Global monetary conditions are in a period of transition as multiple central banks have tapered asset purchases and raised policy rates. We see opportunities in emerging markets, reflecting prospects for a wider recovery in the quarters ahead, earnings growth potential and attractive valuations. Despite these potential catalysts, we are mindful that markets will experience volatility, and we remain closely attuned to risks.

In terms of Fund positioning, we favor a blend of investments in cyclical and secular growth areas, in addition to those tied to demand in commodities, select reopening stories and defensives. We own companies with flexible balance sheets, supportive valuations, and the ability to deliver earnings growth in a challenging environment. From a sector perspective, we see opportunities in consumer discretionary, financials, technology, materials, and energy with compelling fundamentals. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in emerging 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 Evolving World Growth Fund

ANNUALIZED RETURN: SINCE INCEPTION (8/15/08) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.60%, Class C shares is 2.34% and Class I shares is 1.35%. 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

OVERVIEW

The Fund invests in equities of companies around the globe. We seek firms that demonstrate key growth characteristics, including increasing profit margins and high returns on invested capital.

KEY FEATURES

^◼  Pursues, the best risk/reward opportunities across countries, market capitalizations and sectors.

^◼  Seeks global growth companies that may benefit from secular themes, such as exponential demand for information and entertainment.

^◼  Takes environmental, social and governance (ESG) factors into account.

PORTFOLIO FIT

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

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

CALAMOS GLOBAL EQUITY FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the six months ended April 30, 2022 ("semiannual period"), Calamos Global Equity Fund returned -20.94% (Class I shares at net asset value) versus the -11.11% return for the MSCI World Index and the -11.45% return for the MSCI ACWI Index over the period. The Fund's return was ahead of its category peer average in the period, landing in the 44th percentile of the Morningstar Global Large-Stock Growth category.

We believe the Fund's compelling medium and long-term performance record demonstrates the Fund's ability to generate excess returns over complete market cycles and varied investment environments. Since its inception on March 2, 2007, the Fund has returned 8.71% on an annualized basis (Class I shares at net asset value) compared with a 6.91% return for the MSCI World Index and 6.53% return for the MSCI ACWI Index.

What factors influenced performance during the semiannual period?

Global stocks struggled in the semiannual period as investors traversed a global landscape characterized by higher inflation, rising interest rates, and heightened geopolitical tension. Looking ahead, investors and companies have lowered expectations in light of the risks presented by interest rates, the war in Ukraine, supply chain disruptions, and high commodity prices. While Covid has largely transitioned from a pandemic to endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

The Fund trailed the index over the semiannual period due to lagging individual security selection. Many of our Fund holdings in global companies with cyclical and secular growth characteristics trailed the more narrow, defensive market sectors and industries that held up relatively better amid the broad sell-off.

Positive Influences on Performance

Energy. The Fund's average overweight stance and leading security selection in energy drove relative performance. Specifically, oil & gas exploration & production and integrated oil & gas represented major contributors.

Negative Influences on Performance

Information Technology. Over the period, security selection and an average overweight stance within information technology weakened relative results, as holdings in the semiconductors and semiconductor equipment industries curbed relative 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

*  Data is as of 4/30/22. Morningstar category percentile ranking is based on annualized total return for the 1-year, 3-year, 5-year and 10-year periods. Calamos Global Equity Fund Class I Shares were in the 47th, 9th, 25th and 65th percentiles of 360, 311, 273 and 168 funds for the 1-year, 3-year, 5-year and 10-year periods, respectively, for the Morningstar Global Large-Stock category.

Calamos Global Equity Fund

investment team evaluates macroeconomic factors and growth opportunities, and actively integrates them into the investment decision-making process.

^◼  The Fund is positioned with a combination of cyclical and secular growth opportunities, including commodities exposure, reopening/recovery stories and select defensives.

^◼  Technology, consumer discretionary, health care, financials, industrials, and energy represent the largest sector weights in the Fund. Key industry positions include pharmaceuticals, semiconductors, diversified banks, aerospace and defense, interactive media, and oil & gas.

^◼  We own a range of energy and materials holdings in companies positioned to benefit from global supply-and-demand dynamics and attractive capital efficiency.

^◼  We have an underweight stance in more defensive areas including utilities, real estate, consumer staples and traditional telecoms.

^◼  We own a set of cyclical and secular growth opportunities in the US, favoring businesses with the ability to grow near-term earnings and relatively supportive valuations.

^◼  In Europe, we own diversified holdings that reflect a blend of end markets and business types positioned in cyclicals in addition to commodity exposures, select reopening stories, and defensive areas.

^◼  We own select positions in emerging markets within key demand areas such as semiconductors, branded apparel, interactive media, and higher quality financials.

^◼  We have a modest weight in Japan. We own higher quality companies with attractive business models positioned to benefit from improving supply chains and global demand.

What closing thoughts do you have for Fund shareholders?

Global stocks continue to navigate a set of formidable crosscurrents. We are analyzing many aspects of economic activity, alongside the geopolitical backdrop, key policy actions and corporate earnings. Global monetary conditions are in a period of transition as multiple central banks have tapered asset purchases and raised interest rates in recent months. We see opportunities in global stocks that may benefit from normalizing supply chains and inflation in the months ahead, continued earnings growth potential, and a range of exploitable valuation differences across regions. Despite these tailwinds, we are mindful that markets will experience volatility and we remain closely attuned to risks.

In terms of Fund positioning, we favor investments in companies with advantaged business models, flexible balance sheets, supportive valuations, and the ability to deliver earnings growth. From a sector perspective, we see opportunities in technology, consumer discretionary, industrials, health care, energy, and materials with compelling fundamentals. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in global 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 Global Equity Fund

ANNUALIZED RETURN: SINCE INCEPTION (3/1/07) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.58%, Class C shares is 2.33%, Class I shares is 1.33% and Class R6 shares 1.27%. 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).

Calamos Global Equity Fund

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 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.

The Morningstar World Large-Stock Growth Category comprises international funds having 20% to 60% of stocks invested in the United States.

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

CALAMOS GLOBAL OPPORTUNITIES FUND

INVESTMENT TEAM DISCUSSION

How has the Fund performed?

For the six months ended April 30, 2022 ("semiannual period"), Calamos Global Opportunities Fund returned -15.65% (Class I shares at net asset value) versus a -11.45% return for the MSCI ACWI Index and -11.11% return for the MSCI World Index.

Since Class I shares inception on September 18, 1997, the Fund has returned 7.57% on an annualized basis versus a 6.64% return for the MSCI ACWI Index and 6.83% return for the MSCI World Index. We manage the Fund with the goal of achieving upside equity participation and potential downside risk mitigation over full market cycles. We believe this performance demonstrates the Fund's ability to generate attractive long-term returns while pursuing a risk-managed investment approach.

What factors influenced performance?

Global stocks and convertible securities struggled in the semiannual period as markets traversed a global landscape characterized by higher inflation, rising interest rates, and heightened geopolitical tension. Looking ahead, investors and companies have lowered expectations considering the risks presented by interest rates, the war in Ukraine, supply chain disruptions, and high commodity prices. While Covid has largely transitioned from a pandemic to an endemic phase, lockdowns in China still threaten the course of more normal economic activity globally.

Pursuant to our risk-managed equity objective, the Fund navigated volatile markets while employing an active blend of common stocks, convertibles, and options. The Fund's return trailed the index over the semiannual period due to lagging individual security selection. Our holdings in global companies with cyclical and secular growth characteristics trailed the more narrow, defensive market sectors and industries that held up relatively better amid the broad sell-off across markets.

Positive Influences on Performance

Energy. The Fund's favorable security selection and average overweight stance in energy promoted relative returns. In particular, our holdings in oil & gas exploration & production and integrated oil & gas were sources of strength.

Consumer Discretionary. In consumer discretionary, security selection in the automobile manufacturers and general merchandise stores industries added to the Fund's performance

OVERVIEW

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

KEY FEATURES

^◼  Favors companies that source varied revenue streams and strive to generate high-quality growth fundamentals.

^◼  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 along with the potential for lower volatility over market cycles.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos Global Opportunities 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.

Negative Influences on Performance

Information Technology. Over the period, selection within the information technology sector held back relative performance, as holdings in the data processing & outsourced services and semiconductor equipment industries lagged.

Financials. Security selection and an average underweight position in financials also held back relative results. Specifically, diversified banks and our lack of participation in multi-sector holdings hindered return.

Geographic Performance

From a regional standpoint, the Fund benefitted from security selection and an underweight allocation in EMEA. Specifically, our lack of exposure in Russia and Poland represented significant contributors. Moreover, favorable security selection and an overweight allocation in Canada added value to Fund performance.

Conversely, selection in Europe, particularly holdings in the Netherlands and Switzerland, detracted from the Fund's performance. In addition, the Fund's relative security selection in the United States weakened relative 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, actively integrating them into the investment decision-making process.

^◼  The Fund is positioned with a combination of cyclical and secular growth opportunities, including commodities exposure, reopening/recovery stories, and select defensives.

^◼  Consumer discretionary, technology, health care, financials, and industrials represent the largest sector weights. Key industry positions include pharmaceuticals, semiconductors, diversified banks, interactive media & services, autos, and metals & mining.

^◼  We own a range of energy and materials holdings in companies positioned to benefit from global supply-and-demand dynamics and attractive capital efficiency.

^◼  We have an underweight stance in certain defensive areas including utilities, real estate, and more traditional telecoms.

^◼  We own cyclical and secular growth opportunities in the US, favoring businesses with the ability to grow near-term earnings and relatively supportive valuations.

^◼  We own diversified holdings in Europe with a blend of end markets and business types. The Fund is positioned across cyclicals, commodities as well as select reopening and defensive areas.

^◼  We hold positions in emerging markets that offer higher-quality attributes in demand areas such as semiconductors, interactive media, banking and insurance.

^◼  We have modest weight in Japan, which includes higher-quality companies with attractive business models positioned to benefit from improving supply chains and global demand.

Calamos Global Opportunities Fund

What closing thoughts do you have for Fund shareholders?

Global markets continue to navigate a set of formidable crosscurrents. We are analyzing many aspects of economic activity, key policy actions, corporate earnings, and geopolitical events. Global monetary conditions are in a period of transition as multiple central banks have tapered asset purchases and raised interest rates in recent months. We see opportunities in global stocks and convertibles that may benefit from normalizing supply chains and inflation in the months ahead, continued earnings growth potential, and a range of exploitable valuation differences across regions.

Despite these tailwinds, we are mindful that markets will experience volatility, and we remain closely attuned to risks. As markets navigate geopolitical risks, monetary policy, and inflation, we believe the Fund's focus on providing lower-volatility global equity market participation over full market cycles will serve it well. We favor investments in companies with flexible balance sheets, supportive valuations, and the ability to deliver earnings growth. From a sector perspective, we see opportunities in technology, consumer discretionary, industrials, health care, energy and materials with compelling fundamentals. Our active, risk-managed investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in global markets.

Calamos Global Opportunities Fund

ANNUALIZED RETURN: SINCE INCEPTION (9/18/97) THROUGH 4/30/22

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 4/30/22

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/1/22, the Fund's gross expense ratio for Class A shares is 1.45%, Class C shares is 2.20% and Class I shares is 1.20%. 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.

Morningstar World Allocation funds seek to provide both capital appreciation and income by investing in three major areas: stocks, bonds and cash. While these portfolios do explore the whole world, most of them focus on the US, Canada, Japan and the larger markets in Europe. It is rare for such portfolios to invest more than 10% of their assets in emerging markets. These portfolios typically have at least 10% of assets in bonds, less than 70% of assets in stocks, and at least 40% of assets in non-US stocks or bonds.

Calamos Global Opportunities Fund

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 International Small Cap Growth Fund

CALAMOS INTERNATIONAL SMALL CAP GROWTH FUND

INVESTMENT TEAM DISCUSSION

Please discuss the new Calamos International Small Cap Growth Fund's strategy and role within an asset allocation.

Recently launched on March 30, 2022, we are pleased to introduce the Calamos International Small Cap Growth Fund, which in simple terms seeks out securities that offer the best opportunities for growth. It does so by providing investors exposure to an asset class often under-represented in portfolios with the potential for diversification and alpha opportunities. Among its benefits, the Fund offers:

^◼  Meaningful diversification. International small cap stocks are less correlated to the US large and small cap markets, which makes them an excellent means to diversify a portfolio. Non-US small caps are tied more closely to their local economies, serve different customers, operate in different macroeconomic environments, and thereby provide different sources of earnings. The Fund seeks investments in companies with superior earnings growth potential coupled with financial strength and flexibility.

^◼  The potential to add alpha. The international small cap universe has the greatest number of stocks and fewest analysts per stock. This relative lack of coverage creates an opportunity for the Calamos team to uncover misunderstood or less followed companies, recognizing potential catalysts in advance of the broader market.

^◼  A long-tenured investment team with a history of success identifying high-potential companies within key secular themes. These include promising businesses in mobility and connectivity, mass digitization, artificial intelligence and automation, global demographic shifts as well as advances in nanotech, biotech and genetics.

What is your outlook for international small cap growth stocks?

International stocks continue to navigate a set of formidable crosscurrents. We are analyzing many aspects of economic activity, alongside geopolitical events, key policy actions and corporate earnings. Global monetary conditions are in a period of transition as multiple central banks have tapered asset purchases and raised interest rates in recent months. We see opportunities in foreign small cap stocks that should benefit from normalizing supply chain and inflation dynamics, earnings growth potential, and relatively weak sentiment and positioning. Despite these potential tailwinds, we are mindful that markets will experience volatility and we remain closely attuned to risks.

OVERVIEW

The Fund seeks long-term capital appreciation by investing in compelling international small capitalization companies with superior earnings growth potential coupled with financial strength and flexibility.

KEY FEATURES

^◼  Provides access to an expansive opportunity set of small cap investments outside the United States, including businesses in emerging and frontier markets.

^◼  Our long-tenured Investment team has experience managing portfolios across multiple market cycles.

PORTFOLIO FIT

The Fund can provide an attractive asset-allocation building block often under-represented in US investors' portfolios. By diversifying into this less correlated asset class, investors may be able to offset declines in the overall market and reduce their portfolio's volatility with the potential for significant equity upside.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS

Calamos International 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.

In terms of Fund positioning, we favor investments in companies with near-term earnings growth potential, flexible balance sheets, relatively supportive valuations, and advantaged business models. From a sector perspective, we see opportunities in industrials, consumer discretionary, technology, materials, and energy with attractive fundamentals. Our active investment approach and long-term perspective positions us to take advantage of the volatility and opportunities in international small caps.

Calamos International Small Cap Growth Fund

AVERAGE ANNUAL TOTAL RETURN^† AS OF 4/30/22

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 3/30/22, the Fund's gross expense ratio for Class A shares is 2.07%, Class C shares is 2.82%, Class I shares is 1.82% and Class R6 shares is 1.71%. The Fund's investment advisor has contractually agreed to reimburse Fund expenses through March 31, 2025 to the extent necessary so that Total Annual Fund Operating Expenses of Class A shares, Class C shares and Class I shares are limited to 1.35%, 2.10% and 1.10% of average net assets, respectively. The Fund's investment advisor has contractually agreed to limit the Fund's annual ordinary operating expenses through March 31, 2025 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 sub-transfer 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 LLC ("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 and returns for Class C shares have been adjusted for the contingent deferred sales charge (CDSC).

NOTES:

The benchmark MSCI ACWI ex USA Small Cap Index captures small cap representation across 22 of 23 Developed Markets (DM) countries (excluding the US) and 25 Emerging Markets (EM) countries.

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 Sustainable Equities Fund

OVERVIEW

The Fund seeks high-quality growth companies with strong environmental, social and governance (ESG) characteristics. Employing an integrated, fundamental and proprietary screening process, the Fund can invest in developed and developing economies across market capitalizations.

KEY FEATURES

^◼  Aims for above-average returns with lower volatility by focusing on companies that generate higher returns on capital, offer better growth prospects, and maintain a competitive edge.

^◼  Invests in companies with strong ESG characteristics, which we believe are better equipped to adapt to change while avoiding liabilities, thereby contributing to return potential and risk reduction.

^◼  Managed according to a time-tested proprietary process developed by our seasoned investment team, who established one of the first sustainable research platforms and helped set standards for ESG portfolios.

PORTFOLIO FIT

The Fund can serve as a global equity allocation for investors seeking above-average returns with potentially lower volatility from a portfolio of high-quality, ESG-principled companies offering enhanced prospects for growth.

FUND NASDAQ SYMBOLS

FUND CUSIP NUMBERS