Transamerica Bond (IDITX) N-CSRCertified annual shareholder report (management investment company)

Table of Contents

Table of Contents

Table of Contents

DECEMBER 31, 2019

Beginning January 1, 2021, as permitted by regulations adopted by the Securities and Exchange Commission, the fund intends to no longer mail paper copies of the fund’s shareholder reports, unless you specifically request paper copies of the reports from the fund or your financial intermediary (such as broker-dealer or bank). Instead, the reports will be made available on a website and you will be notified by mail each time a report is posted and provided with a website link to access the report.

If you already elected to receive shareholder reports electronically (“e-delivery”), you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the fund electronically anytime by contacting your financial intermediary or, if you are a direct shareholder with the fund, by calling 1-888-233-4339.

You may elect to receive all future reports in paper free of charge. If you invest through a financial intermediary, you can contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports where the fund is held through that intermediary. If you are a direct shareholder with the fund, you can call 1-888-233-4339 to let the fund know you wish to continue receiving paper copies of your shareholder reports. That election will apply to all Transamerica funds held directly with the fund complex.

Customer Service:1-888-233-4339

1801 California St., Suite 5200 Denver, CO 80202

Distributor: Transamerica Capital, Inc.

www.transamerica.com

Table of Contents

Table of Contents

Authorized for distribution only when accompanied or preceded by a prospectus. Investors should carefully consider a fund’s investment goals, risks, charges and expenses before investing. A prospectus contains this and other information; please read it carefully before investing.

Table of Contents

Dear Shareholder,

On behalf of Transamerica Funds, we would like to thank you for your continued support and confidence in our products as we look forward to continuing to serve you and your financial professional in the future. We value the trust you have placed in us.

This annual report provides certain information about the investments and performance of your Fund(s) during the fiscal year. The Securities and Exchange Commission currently requires that annual and semi-annual reports be sent to all shareholders. This report ended December 31, 2019 covers the12-month period ended December 31, 2019.

We believe it is important to understand market conditions over the fiscal year to provide a context for reading this report. As the year began, markets had reacted negatively to steadily rising interest rates and the fear that the U.S. Federal Reserve (“Fed”) was possibly on the verge of a major monetary policy error, that of raising rates into a slowing economy. The S&P 500^® had declined by approximately 20% from its September 2018 high and credit spreads increased considerably as well. This negative sentiment had also extended into the international markets where both developed and emerging markets had suffered losses in excess of U.S. equities. While the ongoing U.S./China trade dispute shared some of the blame for investor angst going into 2019, most eyes were squarely on the Fed and what the path of interest rates might be for the new year. As the calendar turned to 2019, however, the Fed moderated its tone to one of patience, signaling that further rate hikes were likely off the table for the time being. U.S. equity markets reacted favorably in response and approachedall-time highs by late spring 2019.

U.S./China trade talks continued through the first few months of 2019 with little progress, and in May negotiations deteriorated as the U.S. announced a new round of tariffs. China immediately responded with tariffs of its own on U.S. exports. Equity markets initially declined on this news, however, the Fed responded to these renewed trade tensions by signaling it would “act as appropriate to sustain the expansion” which served to contain fears of an economic slowdown. The Fed then proceeded to cut the Fed Funds rate by 0.25% at three consecutive meetings from July through October, taking its policy rate down to a target range of 1.50%—1.75%. These represented the first interest rate cuts since the Fed had begun its tightening campaign in December of 2015, and global equity and credit markets responded favorably.

Markets finished the fiscal year strong as U.S./China trade relations improved and expectations of a stable growth economy combined with benign inflation and lower interest rates helped to emphasize optimism for the year ahead. While the manufacturing sector exhibited some weakness, consumer spending remained strong. Although the drama of impeachment and election uncertainties loomed over Washington, investors seem to have taken thosenon-market related developments in stride while focusing on the broader investment landscape featuring the lowest unemployment rate in fifty years, higher wages and the prospect of rising corporate earnings growth. The S&P 500^®, NASDAQ and Dow Jones Industrial Average all closed the year near their highest levels ever.

For the12-month period ended December 31, 2019, the S&P 500^® Index returned 31.49% while the MSCI EAFE Index, representing international developed market equities, returned 22.66%. During the same period, the Bloomberg Barclays U.S. Aggregate Bond Index returned 8.72%. Please keep in mind that it is important to maintain a diversified portfolio as investment returns have historically been difficult to predict.

In addition to your active involvement in the investment process, we firmly believe that a financial professional is a key resource to help you build a complete picture of your current and future financial needs. Financial professionals are familiar with the market’s history, including long-term returns and volatility of various asset classes. With your financial professional, you can develop an investment program that incorporates factors such as your goals, your investment timeline and your risk tolerance.

Please contact your financial professional if you have any questions about the contents of this report, and thanks again for the confidence you have placed in us.

Sincerely,

Bloomberg Barclays U.S. Aggregate Bond Index: Measures investment grade, U.S. dollar denominated, fixed-rate taxable bonds, including Treasuries, government-related and corporate securities, as well as both mortgage- and asset-backed securities.

MSCI EAFE Index: A free float-adjusted market capitalization index that is designed to measure the equity market performance of developed markets, excluding the U.S. and Canada.

S&P 500^®: A market-capitalization weighted index of 500 large U.S. companies with common stock listed on the New York Stock Exchange or NASDAQ Stock Market.

The views expressed in this report reflect those of the portfolio managers only and may not necessarily represent the views of Transamerica Funds. These views are as of the date of this report and are subject to change based upon market conditions. These views should not be relied upon as investment advice and are not indicative of trading intent on behalf of Transamerica Funds. Investing involves risk, including potential loss of principal. The performance data presented represents past performance does not guarantee future results. Indexes are unmanaged and an investor cannot invest directly in an index.

Table of Contents

Transamerica Stock Index

(unaudited)

MARKET ENVIRONMENT

Equities rebounded in the first quarter as U.S. trade negotiations with China and relatively strong corporate earnings growth helped investor sentiment recover from steep losses at the end of 2018. Stocks and bonds both received a boost from the U.S. Federal Reserve’s (“Fed”) shift to a more dovish tone in January, as it announced it would refrain from interest rate hikes for the foreseeable future. Despite a U.S. government shutdown and global economic weakness, the U.S. economy continued to exhibit a tight labor market, low inflation and slowing but stable economic growth.

In the second quarter, the prospect of lower interest rates generally provided a boost to equities. Renewed trade concerns contributed to volatility during the quarter, with the S&P 500^® (“S&P 500^®” or “Index”) dropping after President Trump threatened to increase tariffs against China and Mexico. Treasury yields also declined and the resulting negative spread between10-year and3-month yields also added to market uncertainty.

Trade tensions were a key focus for domestic and global investors in the third quarter. The Fed lowered interest rates again in August and September to offset that potential risk as well as to combat weak global growth. U.S. manufacturing and consumer sectors showed signs of weakness. Following the10-year and3-month yield spread inversion in the second quarter, the closely monitored 10 and2-year Treasury yield spread inverted briefly for the first time since the global financial crisis, but ended the quarter in positive territory.

In the fourth quarter, expectations of a U.S.-China trade deal, strong economic growth and easing monetary policy boosted investors’ appetite for risk, although there were still signs of weakness, including in manufacturing. Despite the strength of the U.S. economy, the Fed cut interest rates again in October, the third reduction of the year.

PERFORMANCE

For the year ended December 31, 2019, Transamerica Stock Index, Class R4 returned 31.14%. By comparison, its benchmark, the S&P 500^®, returned 31.49%.

STRATEGY REVIEW

The Fund seeks investment results, before fees and expenses that correspond to the performance of the S&P 500^®. The Fund takes positions in securities that, in combination, should have similar return characteristics as the return of the Index. The Index is designed to provide a comprehensive measure oflarge-cap stock performance. It is an unmanaged, market capitalization-weighted index composed of large-capitalization U.S. equities.

From a sector perspective, all sectors in the S&P 500^® had positive returns. The largest positive returns came from the information technology, communication services, and financials sectors. The lowest contributors for the year were the energy, health care, and materials sectors. The primary drivers of tracking difference between the Fund and the Index during the year were fees and expenses, slight mismatches in security weightings versus the Index, cash drag and transaction costs.

Jennifer Hsui, CFA

Greg Savage, CFA

Rachel Aguirre

Alan Mason

Amy Whitelaw

Co-Portfolio Managers

BlackRock Fund Advisors

Page    2

Table of Contents

Transamerica Stock Index

(unaudited)

^(A) The S&P 500^® is a market-capitalization weighted index of 500 large U.S. companies with common stock listed on the NYSE or NASDAQ.

The Fund’s benchmark is an unmanaged index used as a general measure of market performance. Calculations assume dividends and capital gains are reinvested and do not include any managerial expenses. The 10 Year or Since Inception of Fund calculation is based on the previous 10 years or since the inception date of the Fund, whichever is more recent. You cannot invest directly in an index.

The performance data presented represents past performance and does not guarantee future results. Performance data does not reflect the deduction of taxes that would be paid on Fund distributions or the redemption of Fund shares. Investment return and principal value will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than performance quoted. Please see www.transamerica.com for performance data current to the most recent month-end. Returns include the reinvestment of dividends and capital gains. Fund shares are sold without a sales load. Net asset value (NAV) returns include reinvestment of dividends and capital gains but do not reflect the deduction of any sales charges. There are no sales charges for Class R and R4 shares. Class R shares are available only to eligible retirement plans.

Performance figures reflect any fee waivers and/or expense reimbursements by the Investment Adviser and any recoupment by the Investment Adviser of previously waived fees and/or reimbursed expenses. Absent any applicable waivers and/or reimbursements, the performance would be lower.

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

An index fund has operating and other expenses while an index does not. As a result, while the fund will attempt to track the S&P 500^® as closely as possible, it will tend to underperform the index to some degree over time. If an index fund is properly correlated to its stated index, the fund will perform poorly when the index performs poorly.

Equity funds invest in equity securities, which include common stock, preferred stock and convertible securities. Because such securities represent ownership in a corporation, they tend to be more volatile than fixed income or debt securities, which do not represent ownership.

Page    3

Table of Contents

Transamerica Stock Index

DISCLOSURE OF EXPENSES

(unaudited)

SHAREHOLDER EXPENSES

As a shareholder in the Fund, you will bear the ongoing costs (such as the investment advisory fees and other expenses) of managing the corresponding S&P 500 Index Master Portfolio (“Master Portfolio”), in which the Fund invests. You will also bear the cost of operating the Fund (such as management fees, distribution fees, and other expenses).

The following example is intended to help you understand your ongoing costs (in dollars and cents) of investing in the Fund and to compare these costs with the ongoing costs of investing in other funds.

The example is based on an investment of $1,000 invested at July 1, 2019, and held for the entiresix-month period until December 31, 2019.

ACTUAL EXPENSES

The information in the table below provides information about actual account values and actual expenses. You may use the information in these columns, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = $8.60), then multiply the result by the number in the appropriate column for your share class titled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period. If your account is an IRA, your expenses may have included an additional annual fee. The amount of any fee paid during thesix-month period can decrease your ending account value.

HYPOTHETICAL EXAMPLE FOR COMPARISON PURPOSES

The information in the table below provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratios and assumed rates of return of 5% per year before expenses, which are not the Fund’s actual returns. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in your Fund versus other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds. As in the case of the actual expense example, if your account is subject to an IRA fee, the amount of the fee paid through your account would increase the hypothetical expenses you would have paid during the period and decrease the hypothetical ending account value.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges and brokerage commissions paid on purchases and sales of Fund shares. Therefore, the information under the heading “Hypothetical Expenses” is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. If any of these transaction costs were included, your costs would be higher. The expenses shown in the table do not reflect any fees that may be charged to you by brokers, financial intermediaries, or other financial institutions.

Page    4

Table of Contents

Transamerica Stock Index

The Notes to Financial Statements are an integral part of this report.

Page    5

Table of Contents

Transamerica Stock Index

STATEMENT OF CHANGES IN NET ASSETS

For the years ended:

The Notes to Financial Statements are an integral part of this report.

Page    6

Table of Contents

Transamerica Stock Index

FINANCIAL HIGHLIGHTS

For a share outstanding during the period and years indicated:

For a share outstanding during the period and years indicated:

The Notes to Financial Statements are an integral part of this report.

Page    7

Table of Contents

Transamerica Stock Index

NOTES TO FINANCIAL STATEMENTS

At December 31, 2019

1. ORGANIZATION

Transamerica Funds (the “Trust”) is anopen-end management investment company registered under the Investment Company Act of 1940, as amended (the “1940 Act”). The Trust applies investment company accounting and reporting guidance. Transamerica Stock Index (the “Fund”) is a series of the Trust and invests all of its investable assets in the S&P 500 Index Master Portfolio (the “Master Portfolio”).

The financial statements of the Master Portfolio are included within this report and should be read in conjunction with the Fund’s financial statements.

This report must be accompanied or preceded by the Fund’s current prospectus, which contains additional information about the Fund, including risks, as well as investment objectives and strategies.

Transamerica Asset Management, Inc. (“TAM”) serves as investment manager for the Fund pursuant to an investment management agreement. TAM provides continuous and regular investment management services to the Fund. TAM supervises the Fund’s investments, conducts its investment program and provides supervisory, compliance and administrative services to the Fund.

TAM is responsible for all aspects of theday-to-day management of the Fund. TAM may in the future retain one or moresub-advisers to assist in the management of the Fund.

TAM’s investment management services also include the provision of supervisory and administrative services to the Fund. These services include performing certain administrative services for the Fund and supervising and overseeing the administrative, clerical, recordkeeping and bookkeeping services provided to the Fund by State Street Bank and Trust Company (“State Street”), to whom TAM has outsourced the provision of certain services as described below: to the extent agreed upon by TAM and the Fund from time to time, monitoring and verifying the custodian’s daily calculation of the Net Asset Values (“NAV”); shareholder relations functions; compliance services; valuation services; assisting in due diligence and in the oversight and monitoring of certain activities ofsub-advisers and certain aspects of Fund investments; assisting with Fund combinations and liquidations; oversight of the preparation and filing, and review, of all returns and reports, in connection with federal, state and local taxes; oversight and review of regulatory reporting; supervising and coordinating the Fund’s custodian and dividend disbursing agent and monitoring their services to the Fund; assisting the Fund in preparing reports to shareholders; acting as liaison with the Fund’s independent public accountants and providing, upon request, analyses, fiscal year summaries and other audit related services; assisting in the preparation of agendas and supporting documents for and minutes of meetings of trustees and committees of trustees; assisting in the preparation of regular communications with the trustees; and providing personnel and office space, telephones and other office equipment as necessary in order for TAM to perform supervisory and administrative services to the Fund.

2. SIGNIFICANT ACCOUNTING POLICIES

In preparing the Fund’s financial statements in accordance with Generally Accepted Accounting Principles in the United States of America (“GAAP”), estimates or assumptions (which could differ from actual results) may be used that affect reported amounts and disclosures. The following is a summary of significant accounting policies followed by the Fund.

Investment valuation:The value of the Fund’s investment in the Master Portfolio, reflected within the Statement of Assets and Liabilities, displays the Fund’s proportional interest in the net assets of the Master Portfolio.

The valuation policy for the underlying securities held by the Master Portfolio is discussed in the Master Portfolio’s Notes to Financial Statements, which accompany this report.

Security transactions and investment income:The Fund is allocated its proportional share of income and expenses on a daily basis from its investment in the Master Portfolio. All of the net investment income, as well as the realized and unrealized gains and losses from the security transactions of the Master Portfolio are allocated pro rata among the investors and recorded by the Fund on a daily basis.

Multiple class operations, income, and expenses:Income,non-class specific expenses, and realized and unrealized gains and losses are allocated to each class daily based upon net assets. Each class bears its own specific expenses in addition to the allocatednon-class specific expenses.

Distributions to shareholders:Distributions are recorded on theex-dividend date and are determined in accordance with federal income tax regulations, which may differ from GAAP.

Page    8

Table of Contents

Transamerica Stock Index

NOTES TO FINANCIAL STATEMENTS (continued)

At December 31, 2019

2. SIGNIFICANT ACCOUNTING POLICIES (continued)

Indemnification:In the normal course of business, the Fund enters into contracts that contain a variety of representations that provide general indemnifications. The Fund’s maximum exposure under these arrangements is unknown, as this would involve future claims that may be made against the Fund and/or its affiliates that have not yet occurred. However, based on experience, the Fund expects the risk of loss to be remote.

3. BORROWINGS AND OTHER FINANCING TRANSACTIONS

Interfund lending:The Fund, along with other funds and portfolios advised by TAM, may participate in an interfund lending program pursuant to exemptive relief granted by the Securities and Exchange Commission on January 18, 2017. This program allows the Fund to lend to and borrow from other funds and portfolios advised by TAM. Interfund lending transactions are subject to the conditions of the exemptive relief which place limits on the amount of lending or borrowing the Fund may participate in under the program. Interest earned or paid on an interfund lending transaction will be based on the average of certain current market rates. For the year ended December 31, 2019, the Fund has not utilized the program.

4. FEES AND OTHER AFFILIATED TRANSACTIONS

TAM, the Fund’s investment manager, is directly owned by Transamerica Premier Life Insurance Company (“TPLIC”) and AUSA Holding, LLC (“AUSA”), both of which are indirect, wholly owned subsidiaries of Aegon N.V. TPLIC is owned by Commonwealth General Corporation (“Commonwealth”). Commonwealth and AUSA are wholly owned by Transamerica Corporation, a financial services holding company whose primary emphasis is on life and health insurance, and annuity and investment products. Transamerica Corporation is owned by The Aegon Trust, which is owned by Aegon International B.V., which is owned by Aegon N.V., a Netherlands corporation, and a publicly traded international insurance group.

Transamerica Fund Services, Inc. (“TFS”) is the Fund’s transfer agent. Transamerica Capital, Inc. (“TCI”) is the Fund’s distributor/principal underwriter. TAM, TFS, and TCI are affiliates of Aegon NV.

Certain officers and trustees of the Fund are also officers and/or trustees of TAM, TFS, and TCI. No interested trustee who is deemed an interested person due to current or former service with TAM or an affiliate of TAM receives compensation from the Fund. The Fund does paynon-interested persons (independent trustees), as disclosed in Trustee, CCO and deferred compensation fees within the Statement of Operations.

As of December 31, 2019, the percentage of the Fund’s interest in the Master Portfolio, including any open receivable or payable, is 2.27%.

As of December 31, 2019, the investment manager and/or other affiliated investment accounts held balances of the Fund as follows:

Investment management fees:The Fund pays a contractual management fee to TAM at an annual rate of 0.07% on daily Average Net Assets (“ANA”).

The Fund’s management fee includes its allocated share of the advisory fees based on the interest owned in the corresponding Master Portfolio. The advisory fees are accrued daily and payable monthly at an annual rate of 0.01% of the Master Portfolio’s daily net assets. The investment advisory fees allocated from the Master Portfolio are included within the Statement of Operations within Net investment income (loss) allocated from the Master Portfolio, in Expenses (net of waiver and/or reimbursement). Additionally, TAM serves as the Fund’s investment manager, performing administration as well as investment advisory services. TAM renders investment advisory, supervisory, and administration services under an investment management agreement and the Fund pays a single management fee at a rate of 0.06% of the Fund’s average daily net assets (after waiver and/or reimbursement and recapture). The management fees are reflected in Investment management fees within the Statement of Operations.

TAM has contractually agreed to waive fees and/or reimburse Fund expenses to the extent that the total operating expenses excluding, as applicable, acquired fund fees and expenses, interest, taxes, brokerage commissions, dividend and interest expenses on securities sold short, extraordinary expenses, reorganization expenses and other expenses not incurred in the ordinary course of the Fund’s

Page    9

Table of Contents

Transamerica Stock Index

NOTES TO FINANCIAL STATEMENTS (continued)

At December 31, 2019

4. FEES AND OTHER AFFILIATED TRANSACTIONS (continued)

business, exceed the following stated annual operating expense limits to the Fund’s daily ANA. The expenses waived and/or reimbursed, if any, are included in Expenses waived and/or reimbursed within the Statement of Operations.

Effective April 21, 2017, TAM is permitted to recapture amounts contractually waived and/or reimbursed to a class during any of thethirty-six months from the date on which TAM waived fees and/or reimbursed expenses for the class. A class may recapture and reimburse TAM only if such amount does not cause, on any particular business day of the Fund, the class’s total annual operating expenses (after the recapture is taken into account) to exceed the Operating Expense Limits or any, other lower limit then in effect. Amounts recaptured, if any, by TAM for the year ended December 31, 2019 are disclosed in Recapture of previously waived and/or reimbursed fees within the Statement of Operations.

As of December 31, 2019, the balances available for recapture by TAM for the Fund are as follows:

Distribution and service fees:The Trust has a distribution plan (“Distribution Plan”) pursuant to Rule12b-1 under the 1940 Act. Pursuant to the Distribution Plan, the Trust entered into a distribution agreement with TCI as the Fund’s distributor.

The Distribution Plan requires the Fund to pay distribution fees to TCI as compensation for various distribution activities, not as reimbursement for specific expenses. Under the Distribution Plan and distribution agreement, TCI, on behalf of the Fund, is authorized to pay various service providers, as direct payment for expenses incurred in connection with distribution of the Fund’s shares. The distribution and service fees are included in Distribution and service fees within the Statement of Operations.

The Fund is authorized under the Distribution Plan to pay fees to TCI based on daily ANA of each class up to the following annual rates:

Transfer agent fees: Pursuant to a transfer agency agreement, as amended, the Fund pays TFS a fee for providing services based on the number of classes, accounts and transactions relating to the Fund. The Transfer agent fees included within the Statement of Assets and Liabilities and Statement of Operations represent fees paid to TFS, and other unaffiliated parties providing transfer agent related services.

For the year ended December 31, 2019, transfer agent fees paid and the amounts due to TFS are as follows:

Deferred compensation plan:Under anon-qualified deferred compensation plan effective January 1, 1996, (as amended and restated January 1, 2010), available to the trustees, compensation may be deferred that would otherwise be payable by the Trust to an independent trustee on a current basis for services rendered as trustee. Deferred compensation amounts will accumulate based on the value of the investment option, as elected by the trustee. Balances pursuant to deferred compensation plan are recorded in Trustees, Chief Compliance Officer (“CCO”) and deferred compensation fees within the Statement of Assets and Liabilities. For the year ended December 31, 2019, amounts included in Trustees, CCO and deferred compensation fees within the Statement of Operations reflect total compensation paid to the independent Board members.

Page    10

Table of Contents

Transamerica Stock Index

NOTES TO FINANCIAL STATEMENTS (continued)

At December 31, 2019

5. FEDERAL INCOME TAXES AND DISTRIBUTIONS TO SHAREHOLDERS

The Fund has not made any provision for federal income or excise taxes due to its policy to distribute all of its taxable income and capital gains to its shareholders and otherwise qualify as a regulated investment company under Subchapter M of the Internal Revenue Code. The Fund recognizes the tax benefits of uncertain tax positions only where the position is “more likely than not” to be sustained assuming examination by tax authorities. The Fund’s tax returns remain subject to examination by the Internal Revenue Service and state tax authorities three years from the date of filing for federal purposes and four years from the date of filing for state purposes. Management has evaluated the Fund’s tax provisions taken for all open tax years, and has concluded that no provision for income tax is required in the Fund’s financial statements. If applicable, the Fund recognizes interest accrued related to unrecognized tax benefits in relation to interest and penalties expense in Other within the Statement of Operations. The Fund identifies its major tax jurisdictions as U.S. Federal, the state of Colorado, and foreign jurisdictions where the Fund makes significant investments; however, the Fund is not aware of any tax positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will change materially in the next twelve months.

Distributions are determined in accordance with income tax regulations, which may differ from GAAP. Therefore, distributions determined in accordance with tax regulations may differ significantly in amount or character from net investment income and realized gains for financial reporting purposes. Financial reporting records are adjusted for permanent book/tax differences to reflect tax character. The primary permanent differences are due to partnership basis adjustments. These reclassifications have no impact on net assets or results of operations. Financial records are not adjusted for temporary differences. These permanent reclassifications are as follows:

As of December 31, 2019, the approximate cost for U.S. federal income tax purposes, and the aggregate gross/net unrealized appreciation (depreciation) in the value of investments (including securities sold short and derivatives, if any) are as follows:

As of December 31, 2019, the Portfolio had no capital loss carryforwards available to offset future realized capital gains. During the year ended December 31, 2019, the Portfolio did not have any capital loss carryforwards utilized or expired.

The tax character of distributions paid may differ from the character of distributions shown within the Statement of Changes in Net Assets due to short-term gains being treated as ordinary income for tax purposes. The tax character of distributions paid during 2019 and 2018 are as follows:

As of December 31, 2019, the tax basis components of distributable earnings are as follows:

6. STOCK SPLIT

Effective as of the close of business on the date listed in the subsequent table, the Fund’s Class R4 underwent a stock split. There was no impact to the aggregate market value of shares outstanding. The historical capital share activity presented within the Statement of Changes in Net Assets and the per share data presented within the Financial Highlights have been retroactively adjusted to reflect the stock split. The stock split ratios, net effect on the NAV per share, and the number of shares outstanding as of the date indicated were as follows:

Page    11

Table of Contents

Transamerica Stock Index

NOTES TO FINANCIAL STATEMENTS (continued)

At December 31, 2019

7. CUSTODYOUT-OF-POCKET EXPENSE

In December 2015, State Street, the Fund’s custodian, identified inconsistencies in the way in which clients were invoiced for categories of expenses, particularly those deemedout-of-pocket costs, during an18-year period going back to 1998. The issue was the result of inaccurate billing rates that were not subsequently reviewed or adjusted. The amount of the difference in what was charged and what should have been charged, plus interest, was paid back to the Fund in September 2016 as a reimbursement. The amounts applicable to the Fund, if any, were recognized as a change in accounting estimate and is reflected as a reimbursement of custody fees. This resulted in a decrease in net expenses and an overall increase in net assets. Please reference the Financial Highlights for additional information in regards to the per share impact.

8. LEGAL PROCEEDINGS

On August 27, 2018, Transamerica Asset Management, Inc. (“TAM”), Aegon USA Investment Management, LLC (“AUIM”) and Transamerica Capital, Inc. (“TCI”) reached a settlement with the Securities and Exchange Commission (the “SEC”) that resolved an investigation into asset allocation models and volatility overlays utilized by AUIM when it served assub-adviser to certain Transamerica-sponsored mutual funds, and related disclosures. TAM and TCI serve as investment manager and principal underwriter, respectively, to Transamerica-sponsored mutual funds. TCI also serves as the principal underwriter to the variable life insurance and annuity products through which certain Transamerica-sponsored mutual funds are offered. AUIM, an affiliate of TAM and TCI, serves assub-adviser to a number of Transamerica-sponsored mutual funds.

The SEC’s order instituting administrative andcease-and-desist proceedings (the “Order”) pertains to events that occurred during the period between July 2011 and June 2015, and, among other things, the operation and/or implementation of an asset allocation model utilized by AUIM when it served assub-adviser to certain Transamerica tactical funds and asset allocation funds, the designation of the portfolio manager for certain of these funds as well as the operation and/or implementation of volatility overlays utilized by AUIM when it served assub-adviser to the asset allocation funds. The Order also states that the parties failed to make appropriate disclosures regarding these matters, including in marketing materials, and failed to have adequate compliance policies and procedures. AUIM ceased to serve assub-adviser to the Transamerica tactical funds on April 30, 2015 and to the Transamerica asset allocation funds on June 30, 2015.

Under the terms of the Order, AUIM, TAM and TCI were censured, and agreed, without admitting or denying the findings in the Order, to cease and desist from committing or causing any violations of certain statutory provisions and SEC rules. AUIM agreed to pay civil penalties of $21,000,000, $24,599,896 in disgorgement and $3,682,195 in prejudgment interest. TAM agreed to pay civil penalties of $10,500,000, $15,000,000 in disgorgement and $2,235,765 in prejudgment interest. TCI agreed to pay civil penalties of $4,000,000, $12,000,000 in disgorgement and $1,826,022 in prejudgment interest. The amounts paid in disgorgement, prejudgment interest and civil penalties have been deposited into a Fair Fund for distribution to affected investors. Affected investors are those who purchased or held the relevant mutual funds, variable life insurance and annuity investment portfolios and separately managed account strategies during the period between July 2011 and June 2015. The Order states that these investors are to receive from the Fair Fund the pro rata fees and commissions paid by them during that period, subject to any de minimis threshold.

The settlement does not impose any restrictions on the business or continued ability of AUIM, TAM or TCI to serve the funds.

The foregoing is only a brief summary of the Order. A copy of the Order is available on the SEC’s website at https://www.sec.gov.

The funds are affected by many factors and risks: for example, the risk that thesub-advisers’ judgments and investment decisions, and methods, tools, resources, information, models and analyses utilized in making investment decisions, are incorrect or flawed, do not produce the desired results, and cause the funds to lose value. See “Principal Risks” in the prospectus.

The Order and settlement has no impact on the Fund’s financial statements.

Page    12

Table of Contents

Report of Independent Registered Public Accounting Firm

To the Shareholders and the Board of Trustees of Transamerica Stock Index

Opinion on the Financial Statements

We have audited the accompanying statement of assets and liabilities of Transamerica Stock Index (the “Fund”) (one of the portfolios constituting Transamerica Funds (the “Trust”)), as of December 31, 2019, and the related statement of operations for the year then ended, the statements of changes in net assets for each of the two years in the period then ended, the financial highlights for each of the five years in the period then ended and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Portfolio (one of the portfolios constituting Transamerica Funds) at December 31, 2019, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended and its financial highlights for each of the five years in the period then ended, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Trust’s management. Our responsibility is to express an opinion on the Portfolio’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Trust in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Trust is not required to have, nor were we engaged to perform, an audit of the Trust’s internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Trust’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our procedures included confirmation of securities owned as of December 31, 2019, by correspondence with the custodian and others, or by other appropriate auditing procedures where replies from others were not received. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

We have served as the auditor of one or more Transamerica investment companies since 1995.

Boston, Massachusetts

February 26, 2020

Page    13

Table of Contents

Transamerica Stock Index

SUPPLEMENTAL TAX INFORMATION

(unaudited)

For dividends paid during the year ended December 31, 2019, the Fund designated $11,142,274 of qualified dividend income.

For corporate shareholders, 74% of investment income (dividend income plus short-term gains, if any) qualifies for the dividends received deduction.

For tax purposes, the Fund has made a long-term capital gain designations of $14,078,629 for the year ended December 31, 2019.

Page    14

Table of Contents

Management of the Trust

Board Members and Officers

Each of the funds is supervised by the Board. The S&P 500 Index Master Portfolio is supervised by the Board of Trustees of the Master

Investment Portfolio.

The members of the Board (“Board Members”) and executive officers of the Trust are listed below.

Interested Board Member means a board member who may be deemed an “interested person” (as that term is defined in the 1940 Act) of the Trust because of his current or former service with TAM or an affiliate of TAM. Interested Board Members may also be referred to herein as “Interested Trustees.” Independent Board Member means a Board Member who is not an “interested person” (as defined under the 1940 Act) of the Trust and may also be referred to herein as an “Independent Trustee.”

The Board governs each fund and is responsible for protecting the interests of the shareholders. The Board Members are experienced executives who meet periodically throughout the year to oversee the business affairs of each fund and the operation of each fund by its officers. The Board also reviews the management of each fund’s assets by the investment manager and its respectivesub-adviser.

The funds are among the funds managed and sponsored by TAM (collectively, “Transamerica Fund Family”). The Transamerica Fund Family consists of (i) Transamerica Funds (“TF”); (ii) Transamerica Series Trust (“TST”); (iii) Transamerica ETF Trust (“TET”); and (iv) Transamerica Asset Allocation Variable Funds (“TAAVF”). Transamerica Fund Family consists of 126 funds as of the date of this Annual Report. With the exception of Mr. Smit, none of the Board Members serve on the board of trustees of TET. TET is overseen by a separate board of trustees.

The mailing address of each Board Member is c/o Secretary, 1801 California Street, Suite 5200, Denver, Colorado 80202.

Further information about the Trust’s Board Members and Officers is available in the Trust’s Statement of Additional Information, which can be obtained without charge by calling1-888-233-4339 or visiting the Trust’s website at www.transamerica.com.

The Board Members, their age, their positions with the Trust, and their principal occupations for at least the past five years (their titles may have varied during that period), the number of funds in the Transamerica Fund Family the Board oversees, and other board memberships they hold are set forth in the table below. The length of time served is provided from the date a Board Member became a member of the Board.

Page    15

Table of Contents

Page    16

Table of Contents

Page    17

Table of Contents

Page    18

Table of Contents

Page    19

Table of Contents

Officers

The mailing address of each officer is c/o Secretary, 1801 California Street, Suite 5200, Denver, CO 80202. The following table shows information about the officers, including their year of birth, their positions held with the Trust and their principal occupations during the past five years (their titles may have varied during that period). Each officer will hold office until his or her successor has been duly elected or appointed or until his or her earlier death, resignation or removal.

Page    20

Table of Contents

Page    21

Table of Contents

Page    22

Table of Contents

LIQUIDITY RISK MANAGEMENT PROGRAM (“LRMP”)

(unaudited)

Per initial requirements for SEC Rule 22e-4, TAM established a LRMP in 2018. The Board appointed TAM as the LRMP Administrator in September 2018, and approved the LRMP in March of 2019. In advance of the final compliance date of June 1, 2019, TAM successfully completed the liquidity rule implementation. All Funds were on-boarded to the State Street Global Exchange (SSGX) truView system (a third-party liquidity bucketing tool) at the end of December 2018. TAM currently has policies and procedures established for the day to day monitoring of liquidity risk, and continues to test and improve these policies and procedures as may be required.

Page    23

Table of Contents

Appendix A

S&P 500 Index Master Portfolio

Table of Contents

(This page intentionally left blank)

Table of Contents

Table of Contents

Table of Contents