UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act File Number: 811-04441

T. Rowe Price GNMA Fund

(Exact name of registrant as specified in charter)

100 East Pratt Street, Baltimore, MD 21202

(Address of principal executive offices)

David Oestreicher

100 East Pratt Street, Baltimore, MD 21202

(Name and address of agent for service)

Registrant’s telephone number, including area code: (410) 345-2000

Date of fiscal year end: May 31

Date of reporting period: May 31, 2017

The views and opinions in this report were current as of May 31, 2017. They are not guarantees of performance or investment results and should not be taken as investment advice. Investment decisions reflect a variety of factors, and the managers reserve the right to change their views about individual stocks, sectors, and the markets at any time. As a result, the views expressed should not be relied upon as a forecast of the fund’s future investment intent. The report is certified under the Sarbanes-Oxley Act, which requires mutual funds and other public companies to affirm that, to the best of their knowledge, the information in their financial reports is fairly and accurately stated in all material respects.

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GNMAs and other agency mortgage-backed securities (MBS) produced positive results for the 12-month period ended May 31, 2017, but underperformed the broader U.S. investment-grade bond market. Fixed income markets experienced a broad sell-off following the U.S. presidential election in November, driving yields higher, but bonds recovered later in the reporting period as investors recalibrated their initial expectations that the Trump administration would be able to quickly implement expansionary fiscal policies. The Federal Reserve continued to reinvest in its MBS holdings, but, soon after our reporting period ended, the central bank announced plans to begin tapering its balance sheet later in 2017.

The GNMA Fund returned 1.22% over the 12 months ended May 31, 2017. As shown in the Performance Comparison table, the fund outperformed both the Bloomberg Barclays U.S. GNMA Index and the Lipper GNMA Funds Average. Asset allocation was the largest contributor to the fund’s outperformance. After modest results in the first half of the fiscal year, nearly all of the fund’s gains came in the most recent six months.

After expanding 1.6% in 2016, U.S. gross domestic product growth slowed to a 1.2% annualized pace in the first three months of 2017, according to the Commerce Department’s latest estimate. While first-quarter growth was weak, the underlying trend of moderate U.S. economic expansion seems to remain in place, and initial reports indicate that a rebound is likely in the second quarter. Housing market data remained solid, as the percentage of delinquent or foreclosed loans has been trending lower.

Although the pace of employment growth has moderated compared with the last few years, the labor market remains strong. The unemployment rate fell from 4.7% at the start of the reporting period to 4.3% in May, the lowest level in 16 years, although wage increases have slowed somewhat. Employers added an average of 189,000 new jobs a month for the 12-month period. The annual inflation rate reached a five-year high of 2.7% in February before trailing off in the following months, and any further increases are likely to be gradual as energy prices level off.

Citing an improving labor market and rising inflation, the Federal Reserve raised interest rates twice during our reporting period—and once more on June 14, soon after our reporting period ended. After signaling to financial markets for several months that the case for raising short-term rates had strengthened, Fed officials lifted the federal funds rate 25 basis points in December and followed with additional 25-basis-point increases in March and June. After the series of hikes, the target range for the fed funds rate was 1.00% to 1.25%. The central bank maintained its policy of reinvesting principal payments from its MBS holdings during our reporting period, which has been supportive of the sector, but at its June meeting the Fed said it will begin gradually reducing its balance sheet by the end of this year if economic conditions remain favorable.

Treasury yields across all maturities were higher at the end of May than they were 12 months earlier, with the yield of the 10-year note—which best approximates the maturity of GNMAs and other MBS—rising from 1.84% to 2.21%. The Treasury yield curve flattened during the period as shorter maturities, which are more directly affected by Fed rate increases, rose more than longer-maturity bonds, which are more sensitive to fluctuations in inflation expectations.

Yields declined early in the period, with the 10-year Treasury note hitting a record-low yield of 1.36% in early July, following concerns about slowing global growth and the UK’s vote to leave the European Union. Yields later began rising on speculation that the European Central Bank would begin tapering its asset purchases and expectations that the Fed would proceed with rate hikes given stronger economic data. The Treasury sell-off intensified following the U.S. election as the market priced in the possibility of higher growth, inflation, and debt levels under a Trump administration; as a result, November was the worst month for Treasuries since January 2009.

The yield for the 10-year note reached 2.62%—its high point for the period—in mid-March. However, investor demand for Treasuries increased, and yields started to trend lower as a series of political developments, including the initial failure of the Republican effort to replace the Affordable Care Act, sparked doubts about how quickly the Trump administration would be able to implement its potentially inflationary economic agenda.

It was a challenging year for the MBS market. Concerns about prepayment risk amid the falling rate environment early in our fiscal year were replaced by fears of rising exposure to interest rate risk as expectations for fiscal stimulus following the election led to higher long-term rates. We took a risk-aware approach in positioning the portfolio during this environment, which helped the fund outperform its benchmark and Lipper peer group average. (Performance for the I Class will vary due to its differing fee structure.)

Asset allocation was the largest contributor to relative outperformance, and our out-of-benchmark position in collateralized mortgage obligations (CMOs) was particularly beneficial. We added to our holdings in this subsector of the mortgage market in the first half of our fiscal year and targeted our purchases toward floating rate structures. Floating rate CMOs are less sensitive to interest rate movements and outperformed when rates moved higher. CMOs made up 10% of the portfolio at the end of November, but we subsequently trimmed our position to 4% by the end of the reporting period as the need for protection against higher rates diminished.

GNMAs continued to make up the largest portion of the fund’s assets, but we reduced our position from 94% of net assets to 86% during the past 12 months. We were underweight the benchmark during the period, which helped relative results. We believed the valuations of these securities had become unattractive as a result of heavy demand from overseas investors searching for yield. We also benefited from our positioning within GNMAs. We favored holding liquid 30-year to-be-announced (TBA) GNMAs and had some exposure to loans originated with a smaller balance. Our position in pools of loans originated earlier in this economic cycle provided a greater source of income to our shareholders.

Our small position in asset-backed securities also added value as these short-duration, high-quality assets performed well during the period.

The fund’s yield curve positioning contributed to relative results. In this low-yield environment, we maintained a longer duration than the index during most of the year but made adjustments with the use of interest rate derivatives along the way to preserve income and lower the risks that the portfolio faced from uncertainty in the market. During the 12-month period, our derivatives positions had a positive impact on performance.

The Federal Reserve’s announcement that it expects to begin reducing its MBS holdings later this year could be a headwind for the MBS sector as the market seeks to absorb the additional supply from the central bank. Although the Fed provided some details of its plan for balance sheet normalization in its June 14 statement, uncertainties remain about other details that could have an impact on the market, such as the start date of the program and the terminal size of the balance sheet. Other risks, such as the potential reform of government-sponsored enterprises, are also present.

Although the Fed’s actions could provide technical challenges, the fundamentals of the housing market appear solid, providing support for the sector. Moreover, the liquidity and strong credit quality of agency MBS should remain appealing to fixed income investors, and MBS appear attractive relative to other credit-sensitive sectors.

We structure the portfolio to provide shareholders with the most attractive low-risk opportunities in the market, and we believe we are well positioned for the potential volatility that the sector could face. Balancing the cost of liquidity against risk level is an integral part of our investment and risk-monitoring process. Our management team also uses internally and externally developed quantitative tools to track and manage the risk profile of the portfolio as market conditions change. Security selection is still critical, and we will continue to rely heavily on our extensive team of analysts, who provide careful, fundamental research on individual bonds.

The committee chairman has day-to-day responsibility for managing the portfolio and works with committee members in developing and executing the fund’s investment program.

Even though principal and interest payments on GNMAs are guaranteed, an increase in interest rates can cause the share price to decline, resulting in a loss of principal. Investors in bond funds are also subject to several other types of risk—interest rate risk, credit risk, prepayment risk, extension risk, and derivatives risk. Since the fund invests primarily in GNMAs, which are backed by the full faith and credit of the U.S. government, its exposure to credit risk is low. A mortgage-backed bond, unlike most other bonds, can be hurt when interest rates fall because homeowners tend to refinance and prepay principal. Prepayments can cause the average maturity of the portfolio to shorten, require the fund to reinvest proceeds at lower interest rates, or even cause certain bonds’ prices to fall below what the fund paid for them, resulting in a capital loss. Increased interest rates can cause the fund’s average maturity to lengthen unexpectedly due to a drop in mortgage prepayments. Shareholders are also exposed to derivatives risk, the potential that our investments in these complex and volatile instruments could affect the fund’s share price.

Asset-backed securities: Bonds whose payments are backed by a pool of receivables or other financial assets.

Bloomberg Barclays U.S. GNMA Index: Tracks the performance of mortgage-backed pass-through securities of the Government National Mortgage Association (GNMA). Collateralized mortgage obligation: Bonds backed by mortgage pass-throughs whose cash flows are directed in different ways to different classes. Some classes may have less risk associated with prepayments, and, by default, the other classes will have more prepayment risk.

Commercial mortgage-backed securities (CMBS): Bonds backed by loans on commercial rather than residential properties.

Duration: A measure of a bond fund’s sensitivity to changes in interest rates. For example, a fund with a duration of five years would fall about 5% in price in response to a one-percentage-point rise in interest rates, and vice versa.

Federal funds rate: The interest rate charged on overnight loans of reserves by one financial institution to another in the U.S. The Federal Reserve sets a target federal funds rate to affect the level and direction of market rates.

Gross domestic product: The total market value of all goods and services produced in a country in a given year.

Lipper averages: The averages of available mutual fund performance returns for specified time periods in categories defined by Lipper Inc.

SEC yield (30-day): A method of calculating a fund’s yield that assumes all portfolio securities are held until maturity. Yield will vary and is not guaranteed.

Total return: The annual rate of return on a bond, taking into account interest income, plus appreciation or depreciation. If a bond is held to maturity, its total return equals its yield to maturity.

Weighted average maturity: A measure of a fund’s interest rate sensitivity. In general, the longer the average maturity, the greater the fund’s sensitivity to interest rate changes. The weighted average maturity may take into account the interest rate readjustment dates for certain securities. Money funds must maintain a weighted average maturity of less than 60 days.

Yield curve: A graphic depiction of the relationship between yields and maturity dates for a set of similar securities. A security with a longer maturity usually has a higher yield. If a short-term security offers a higher yield, then the curve is said to be “inverted.” If short- and long-term bonds are offering equivalent yields, then the curve is said to be “flat.”

This chart shows the value of a hypothetical $10,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The result is compared with benchmarks, which may include a broad-based market index and a peer group average or index. Market indexes do not include expenses, which are deducted from fund returns as well as mutual fund averages and indexes.

As a mutual fund shareholder, you may incur two types of costs: (1) transaction costs, such as redemption fees or sales loads, and (2) ongoing costs, including management fees, distribution and service (12b-1) fees, and other fund expenses. The following example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 invested at the beginning of the most recent six-month period and held for the entire period.

Please note that the fund has two share classes: The original share class (Investor Class) charges no distribution and service (12b-1) fee, and the I Class shares are also available to institutionally oriented clients and impose no 12b-1 or administrative fee payment. Each share class is presented separately in the table.

Actual Expenses
The first line of the following table (Actual) provides information about actual account values and expenses based on the fund’s actual returns. You may use the information on this line, together with your account balance, 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 = 8.6), then multiply the result by the number on the first line under the heading “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes
The information on the second line of the table (Hypothetical) is based on hypothetical account values and expenses derived from the fund’s actual expense ratio and an assumed 5% per year rate of return before expenses (not the fund’s actual return). You may compare the ongoing costs of investing in the fund with other funds by contrasting this 5% hypothetical example and the 5% hypothetical examples that appear in the shareholder reports of the other funds. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period.

Note: T. Rowe Price charges an annual account service fee of $20, generally for accounts with less than $10,000. The fee is waived for any investor whose T. Rowe Price mutual fund accounts total $50,000 or more; accounts electing to receive electronic delivery of account statements, transaction confirmations, prospectuses, and shareholder reports; or accounts of an investor who is a T. Rowe Price Personal Services or Enhanced Personal Services client (enrollment in these programs generally requires T. Rowe Price assets of at least $250,000). This fee is not included in the accompanying table. If you are subject to the fee, keep it in mind when you are estimating the ongoing expenses of investing in the fund and when comparing the expenses of this fund with other funds.

You should also be aware that the expenses shown in the table highlight only your ongoing costs and do not reflect any transaction costs, such as redemption fees or sales loads. Therefore, the second line of the table is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. To the extent a fund charges transaction costs, however, the total cost of owning that fund is higher.

T. Rowe Price GNMA Fund (the fund), is registered under the Investment Company Act of 1940 (the 1940 Act) as a diversified, open-end management investment company. The fund seeks high current income consistent with high overall credit quality and moderate price fluctuation by investing at least 80% of its total assets in Government National Mortgage Association securities backed by the full faith and credit of the U.S. government. The fund has two classes of shares: the GNMA Fund (Investor Class) and the GNMA Fund–I Class (I Class). I Class shares generally are available only to investors meeting a $1,000,000 minimum investment or certain other criteria. Each class has exclusive voting rights on matters related solely to that class; separate voting rights on matters that relate to both classes; and, in all other respects, the same rights and obligations as the other class.

Basis of Preparation The fund is an investment company and follows accounting and reporting guidance in the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 (ASC 946). The accompanying financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (GAAP), including, but not limited to, ASC 946. GAAP requires the use of estimates made by management. Management believes that estimates and valuations are appropriate; however, actual results may differ from those estimates, and the valuations reflected in the accompanying financial statements may differ from the value ultimately realized upon sale or maturity.

Investment Transactions, Investment Income, and Distributions Income and expenses are recorded on the accrual basis. Premiums and discounts on debt securities are amortized for financial reporting purposes. Paydown gains and losses are recorded as an adjustment to interest income. Inflation adjustments to the principal amount of inflation-indexed bonds are reflected as interest income. Dividends received from mutual fund investments are reflected as dividend income; capital gain distributions are reflected as realized gain/loss. Dividend income and capital gain distributions are recorded on the ex-dividend date. Income tax-related interest and penalties, if incurred, would be recorded as income tax expense. Investment transactions are accounted for on the trade date. Realized gains and losses are reported on the identified cost basis. Income distributions are declared by each class daily and paid monthly. Distributions to shareholders are recorded on the ex-dividend date.

Class Accounting Shareholder servicing, prospectus, and shareholder report expenses incurred by each class are charged directly to the class to which they relate. Expenses common to both classes and investment income are allocated to the classes based upon the relative daily net assets of each class’s settled shares; realized and unrealized gains and losses are allocated based upon the relative daily net assets of each class’s outstanding shares.

New Accounting Guidance In October 2016, the Securities and Exchange Commission (SEC) issued a new rule, Investment Company Reporting Modernization, which, among other provisions, amends Regulation S-X to require standardized, enhanced disclosures, particularly related to derivatives, in investment company financial statements. Compliance with the guidance is effective for financial statements related to periods ending on or after August 1, 2017; adoption will have no effect on the fund’s net assets or results of operations.

The fund’s financial instruments are valued and each class’s net asset value (NAV) per share is computed at the close of the New York Stock Exchange (NYSE), normally 4 p.m. ET, each day the NYSE is open for business. However, the NAV per share may be calculated at a time other than the normal close of the NYSE if trading on the NYSE is restricted, if the NYSE closes earlier, or as may be permitted by the SEC.

Fair Value The fund’s financial instruments are reported at fair value, which GAAP defines as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The T. Rowe Price Valuation Committee (the Valuation Committee) is an internal committee that has been delegated certain responsibilities by the fund’s Board of Trustees (the Board) to ensure that financial instruments are appropriately priced at fair value in accordance with GAAP and the 1940 Act. Subject to oversight by the Board, the Valuation Committee develops and oversees pricing-related policies and procedures and approves all fair value determinations. Specifically, the Valuation Committee establishes procedures to value securities; determines pricing techniques, sources, and persons eligible to effect fair value pricing actions; oversees the selection, services, and performance of pricing vendors; oversees valuation-related business continuity practices; and provides guidance on internal controls and valuation-related matters. The Valuation Committee reports to the Board and has representation from legal, portfolio management and trading, operations, risk management, and the fund’s treasurer.

Various valuation techniques and inputs are used to determine the fair value of financial instruments. GAAP establishes the following fair value hierarchy that categorizes the inputs used to measure fair value:

Level 1 – quoted prices (unadjusted) in active markets for identical financial instruments that the fund can access at the reporting date

Level 2 – inputs other than Level 1 quoted prices that are observable, either directly or indirectly (including, but not limited to, quoted prices for similar financial instruments in active markets, quoted prices for identical or similar financial instruments in inactive markets, interest rates and yield curves, implied volatilities, and credit spreads)

Observable inputs are developed using market data, such as publicly available information about actual events or transactions, and reflect the assumptions that market participants would use to price the financial instrument. Unobservable inputs are those for which market data are not available and are developed using the best information available about the assumptions that market participants would use to price the financial instrument. GAAP requires valuation techniques to maximize the use of relevant observable inputs and minimize the use of unobservable inputs. When multiple inputs are used to derive fair value, the financial instrument is assigned to the level within the fair value hierarchy based on the lowest-level input that is significant to the fair value of the financial instrument. Input levels are not necessarily an indication of the risk or liquidity associated with financial instruments at that level but rather the degree of judgment used in determining those values.

Valuation Techniques Debt securities generally are traded in the over-the-counter (OTC) market. Securities with remaining maturities of one year or more at the time of acquisition are valued at prices furnished by dealers who make markets in such securities or by an independent pricing service, which considers the yield or price of bonds of comparable quality, coupon, maturity, and type, as well as prices quoted by dealers who make markets in such securities. Securities with remaining maturities of less than one year at the time of acquisition generally use amortized cost in local currency to approximate fair value. However, if amortized cost is deemed not to reflect fair value or the fund holds a significant amount of such securities with remaining maturities of more than 60 days, the securities are valued at prices furnished by dealers who make markets in such securities or by an independent pricing service. Generally, debt securities are categorized in Level 2 of the fair value hierarchy; however, to the extent the valuations include significant unobservable inputs, the securities would be categorized in Level 3.

Investments in mutual funds are valued at the mutual fund’s closing NAV per share on the day of valuation and are categorized in Level 1 of the fair value hierarchy. Financial futures contracts are valued at closing settlement prices and are categorized in Level 1 of the fair value hierarchy. Swaps are valued at prices furnished by an independent pricing service or independent swap dealers and generally are categorized in Level 2 of the fair value hierarchy. Assets and liabilities other than financial instruments, including short-term receivables and payables, are carried at cost, or estimated realizable value, if less, which approximates fair value.

Thinly traded financial instruments and those for which the above valuation procedures are inappropriate or are deemed not to reflect fair value are stated at fair value as determined in good faith by the Valuation Committee. The objective of any fair value pricing determination is to arrive at a price that could reasonably be expected from a current sale. Financial instruments fair valued by the Valuation Committee are primarily private placements, restricted securities, warrants, rights, and other securities that are not publicly traded.

Subject to oversight by the Board, the Valuation Committee regularly makes good faith judgments to establish and adjust the fair valuations of certain securities as events occur and circumstances warrant. For instance, in determining the fair value of troubled or thinly traded debt instruments, the Valuation Committee considers a variety of factors, which may include, but are not limited to, the issuer’s business prospects, its financial standing and performance, recent investment transactions in the issuer, strategic events affecting the company, market liquidity for the issuer, and general economic conditions and events. In consultation with the investment and pricing teams, the Valuation Committee will determine an appropriate valuation technique based on available information, which may include both observable and unobservable inputs. The Valuation Committee typically will afford greatest weight to actual prices in arm’s length transactions, to the extent they represent orderly transactions between market participants, transaction information can be reliably obtained, and prices are deemed representative of fair value. However, the Valuation Committee may also consider other valuation methods such as a discount or premium from market value of a similar, freely traded security of the same issuer; discounted cash flows; yield to maturity; or some combination. Fair value determinations are reviewed on a regular basis and updated as information becomes available, including actual purchase and sale transactions of the issue. Because any fair value determination involves a significant amount of judgment, there is a degree of subjectivity inherent in such pricing decisions, and fair value prices determined by the Valuation Committee could differ from those of other market participants. Depending on the relative significance of unobservable inputs, including the valuation technique(s) used, fair valued securities may be categorized in Level 2 or 3 of the fair value hierarchy.

Valuation Inputs The following table summarizes the fund’s financial instruments, based on the inputs used to determine their fair values on May 31, 2017:

There were no material transfers between Levels 1 and 2 during the year ended May 31, 2017.

During the year ended May 31, 2017, the fund invested in derivative instruments. As defined by GAAP, a derivative is a financial instrument whose value is derived from an underlying security price, foreign exchange rate, interest rate, index of prices or rates, or other variable; it requires little or no initial investment and permits or requires net settlement. The fund invests in derivatives only if the expected risks and rewards are consistent with its investment objectives, policies, and overall risk profile, as described in its prospectus and Statement of Additional Information. The fund may use derivatives for a variety of purposes, such as seeking to hedge against declines in principal value, increase yield, invest in an asset with greater efficiency and at a lower cost than is possible through direct investment, or to adjust portfolio duration and credit exposure. The risks associated with the use of derivatives are different from, and potentially much greater than, the risks associated with investing directly in the instruments on which the derivatives are based. The fund at all times maintains sufficient cash reserves, liquid assets, or other SEC-permitted asset types to cover its settlement obligations under open derivative contracts.

The fund values its derivatives at fair value and recognizes changes in fair value currently in its results of operations. Accordingly, the fund does not follow hedge accounting, even for derivatives employed as economic hedges. Generally, the fund accounts for its derivatives on a gross basis. It does not offset the fair value of derivative liabilities against the fair value of derivative assets on its financial statements, nor does it offset the fair value of derivative instruments against the right to reclaim or obligation to return collateral. The following table summarizes the fair value of the fund’s derivative instruments held as of May 31, 2017, and the related location on the accompanying Statement of Assets and Liabilities, presented by primary underlying risk exposure:

Additionally, the amount of gains and losses on derivative instruments recognized in fund earnings during the year ended May 31, 2017, and the related location on the accompanying Statement of Operations is summarized in the following table by primary underlying risk exposure:

Counterparty Risk and Collateral The fund invests in exchange-traded or centrally cleared derivative contracts, such as futures, exchange-traded options, and centrally cleared swaps. Counterparty risk on such derivatives is minimal because the clearinghouse provides protection against counterparty defaults. For futures and centrally cleared swaps, the fund is required to deposit collateral in an amount specified by the clearinghouse and the clearing firm (margin requirement), and the margin requirement must be maintained over the life of the contract. Each clearinghouse and clearing firm, in its sole discretion, may adjust the margin requirements applicable to the fund.

Collateral may be in the form of cash or debt securities issued by the U.S. government or related agencies. Cash posted by the fund is reflected as cash deposits in the accompanying financial statements and generally is restricted from withdrawal by the fund; securities posted by the fund are so noted in the accompanying Portfolio of Investments; both remain in the fund’s assets. As of May 31, 2017, cash of $1,144,000 and securities valued at $169,000 had been posted by the fund for exchange-traded and/or centrally cleared derivatives.

Futures Contracts The fund is subject to interest rate risk in the normal course of pursuing its investment objectives and uses futures contracts to help manage such risk. The fund may enter into futures contracts to manage exposure to interest rate and yield curve movements, security prices, foreign currencies, credit quality, and mortgage prepayments; as an efficient means of adjusting exposure to all or part of a target market; to enhance income; as a cash management tool; or to adjust portfolio duration and credit exposure. A futures contract provides for the future sale by one party and purchase by another of a specified amount of a specific underlying financial instrument at an agreed-upon price, date, time, and place. The fund currently invests only in exchange-traded futures, which generally are standardized as to maturity date, underlying financial instrument, and other contract terms. Payments are made or received by the fund each day to settle daily fluctuations in the value of the contract (variation margin), which reflect changes in the value of the underlying financial instrument. Variation margin is recorded as unrealized gain or loss until the contract is closed. The value of a futures contract included in net assets is the amount of unsettled variation margin; net variation margin receivable is reflected as an asset, and net variation margin payable is reflected as a liability on the accompanying Statement of Assets and Liabilities. Risks related to the use of futures contracts include possible illiquidity of the futures markets, contract prices that can be highly volatile and imperfectly correlated to movements in hedged security values and/or interest rates, and potential losses in excess of the fund’s initial investment. During the year ended May 31, 2017, the volume of the fund’s activity in futures, based on underlying notional amounts, was generally between 5% and 18% of net assets.

Swaps The fund is subject to interest rate risk in the normal course of pursuing its investment objectives and uses swap contracts to help manage such risk. The fund may use swaps in an effort to manage exposure to changes in interest rates, inflation rates, and credit quality; to adjust overall exposure to certain markets; to enhance total return or protect the value of portfolio securities; to serve as a cash management tool; or to adjust portfolio duration and credit exposure. Swap agreements can be settled either directly with the counterparty (bilateral swap) or through a central clearinghouse (centrally cleared swap). Fluctuations in the fair value of a contract are reflected in unrealized gain or loss and are reclassified to realized gain or loss upon contract termination or cash settlement. Net periodic receipts or payments required by a contract increase or decrease, respectively, the value of the contract until the contractual payment date, at which time such amounts are reclassified from unrealized to realized gain or loss. For bilateral swaps, cash payments are made or received by the fund on a periodic basis in accordance with contract terms; unrealized gain on contracts and premiums paid are reflected as assets and unrealized loss on contracts and premiums received are reflected as liabilities on the accompanying Statement of Assets and Liabilities. For bilateral swaps, premiums paid or received are amortized over the life of the swap and are recognized as realized gain or loss in the Statement of Operations. For centrally cleared swaps, payments are made or received by the fund each day to settle the daily fluctuation in the value of the contract (variation margin). Accordingly, the value of a centrally cleared swap included in net assets is the unsettled variation margin; net variation margin receivable is reflected as an asset and net variation margin payable is reflected as a liability on the accompanying Statement of Assets and Liabilities.

Interest rate swaps are agreements to exchange cash flows based on the difference between specified interest rates applied to a notional principal amount for a specified period of time. Risks related to the use of interest rate swaps include the potential for unanticipated movements in interest or currency rates, the possible failure of a counterparty to perform in accordance with the terms of the swap agreements, potential government regulation that could adversely affect the fund’s swap investments, and potential losses in excess of the fund’s initial investment.

During the year ended May 31, 2017, the volume of the fund’s activity in swaps, based on underlying notional amounts, was generally between 0% and 13% of net assets.

Consistent with its investment objective, the fund engages in the following practices to manage exposure to certain risks and/or to enhance performance. The investment objective, policies, program, and risk factors of the fund are described more fully in the fund’s prospectus and Statement of Additional Information.

Restricted Securities The fund may invest in securities that are subject to legal or contractual restrictions on resale. Prompt sale of such securities at an acceptable price may be difficult and may involve substantial delays and additional costs.

Collateralized Loan Obligations The fund may invest in collateralized loan obligations (CLOs) which are entities backed by a diversified pool of syndicated bank loans. The cash flows of the CLO can be split into multiple segments, called “tranches” or “classes”, which will vary in risk profile and yield. The riskiest segments, which are the subordinate or “equity” tranches, bear the greatest risk of loss from defaults in the underlying assets of the CLO and serve to protect the other, more senior, tranches. Senior tranches will typically have higher credit ratings and lower yields than the securities underlying the CLO. Despite the protection from the more junior tranches, senior tranches can experience substantial losses.

TBA Purchase and Sale Commitments The fund may enter into to-be-announced (TBA) purchase or sale commitments (collectively, TBA transactions), pursuant to which it agrees to purchase or sell, respectively, mortgage-backed securities for a fixed unit price, with payment and delivery at a scheduled future date beyond the customary settlement period for such securities. With TBA transactions, the particular securities to be received or delivered by the fund are not identified at the trade date; however, the securities must meet specified terms, including issuer, rate, and mortgage term, and be within industry-accepted “good delivery” standards. The fund may enter into TBA transactions with the intention of taking possession of or relinquishing the underlying securities, may elect to extend the settlement by “rolling” the transaction, and/or may use TBA transactions to gain or reduce interim exposure to underlying securities. Until settlement, the fund maintains liquid assets sufficient to settle its TBA commitments.

To mitigate counterparty risk, the fund has entered into agreements with TBA counterparties that provide for collateral and the right to offset amounts due to or from those counterparties under specified conditions. Subject to minimum transfer amounts, collateral requirements are determined and transfers made based on the net aggregate unrealized gain or loss on all TBA commitments with a particular counterparty. At any time, the fund’s risk of loss from a particular counterparty related to its TBA commitments is the aggregate unrealized gain on appreciated TBAs in excess of unrealized loss on depreciated TBAs and collateral received, if any, from such counterparty. As of May 31, 2017, cash of $672,000 had been posted by the fund to counterparties for TBAs. Collateral pledged by counterparties to the fund for TBAs consisted of $1,663,000 cash as of May 31, 2017.

Dollar Rolls The fund may enter into dollar roll transactions, pursuant to which it sells a mortgage-backed TBA or security and simultaneously agrees to purchase a similar, but not identical, TBA with the same issuer, rate, and terms on a later date at a set price from the same counterparty. The fund may execute a “roll” to obtain better underlying mortgage securities or to enhance returns. While the fund may enter into dollar roll transactions with the intention of taking possession of the underlying mortgage securities, it may also close a contract prior to settlement or “roll” settlement to a later date if deemed to be in the best interest of shareholders. Actual mortgages received by the fund may be less favorable than those anticipated. The fund accounts for dollar roll transactions as purchases and sales, which has the effect of increasing its portfolio turnover rate.

Mortgage-Backed Securities The fund may invest in mortgage-backed securities (MBS or pass-through certificates) that represent an interest in a pool of specific underlying mortgage loans and entitle the fund to the periodic payments of principal and interest from those mortgages. MBS may be issued by government agencies or corporations, or private issuers. Most MBS issued by government agencies are guaranteed; however, the degree of protection differs based on the issuer. The fund also may invest in stripped MBS, created when a traditional MBS is split into an interest-only (IO) and a principal-only (PO) strip. MBS, including IOs and POs, are sensitive to changes in economic conditions that affect the rate of prepayments and defaults on the underlying mortgages; accordingly, the value, income, and related cash flows from MBS may be more volatile than other debt instruments. IOs also risk loss of invested principal from faster-than-anticipated prepayments.

Other Purchases and sales of portfolio securities other than short-term and U.S. government securities aggregated $44,860,000 and $43,082,000, respectively, for the year ended May 31, 2017. Purchases and sales of U.S. government securities aggregated $6,989,929,000 and $7,086,253,000, respectively, for the year ended May 31, 2017.

No provision for federal income taxes is required since the fund intends to continue to qualify as a regulated investment company under Subchapter M of the Internal Revenue Code and distribute to shareholders all of its taxable income and gains. Distributions determined in accordance with federal income tax regulations may differ 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 but are not adjusted for temporary differences.

The fund files U.S. federal, state, and local tax returns as required. The fund’s tax returns are subject to examination by the relevant tax authorities until expiration of the applicable statute of limitations, which is generally three years after the filing of the tax return but which can be extended to six years in certain circumstances. Tax returns for open years have incorporated no uncertain tax positions that require a provision for income taxes.

Reclassifications to paid-in capital relate primarily to an over-distribution of taxable income not deemed a return of capital for tax purposes. Reclassifications between income and gain relate primarily to the character of paydown gains and losses on asset-backed securities. For the year ended May 31, 2017, the following reclassifications were recorded to reflect tax character (there was no impact on results of operations or net assets):

Distributions during the years ended May 31, 2017 and May 31, 2016, totaled $42,291,000 and $46,337,000, respectively, and were characterized as ordinary income for tax purposes. At May 31, 2017, the tax-basis cost of investments and components of net assets were as follows:

The fund intends to retain realized gains to the extent of available capital loss carryforwards. Net realized capital losses may be carried forward indefinitely to offset future realized capital gains. Further, $5,981,000 of the fund’s available capital loss carryforwards acquired through tax-free reorganizations may be subject to certain limitations on amount or timing of use.

The fund is managed by T. Rowe Price Associates, Inc. (Price Associates), a wholly owned subsidiary of T. Rowe Price Group, Inc. (Price Group). The investment management agreement between the fund and Price Associates provides for an annual investment management fee, which is computed daily and paid monthly. The fee consists of an individual fund fee, equal to 0.15% of the fund’s average daily net assets, and a group fee. The group fee rate is calculated based on the combined net assets of certain mutual funds sponsored by Price Associates (the group) applied to a graduated fee schedule, with rates ranging from 0.48% for the first $1 billion of assets to 0.265% for assets in excess of $650 billion. The fund’s group fee is determined by applying the group fee rate to the fund’s average daily net assets. At May 31, 2017, the effective annual group fee rate was 0.29%.

The I Class is subject to an operating expense limitation (I Class limit) pursuant to which Price Associates is contractually required to pay all operating expenses of the I Class, excluding management fees, interest, expenses related to borrowings, taxes, brokerage, and other non-recurring expenses permitted by the investment management agreement, to the extent such operating expenses, on an annualized basis, exceed 0.05% of average net assets. This agreement will continue until September 30, 2019, and may be renewed, revised, or revoked only with approval of the fund’s Board. The I Class is required to repay Price Associates for expenses previously paid to the extent the class’s net assets grow or expenses decline sufficiently to allow repayment without causing the class’s operating expenses to exceed the I Class limit in effect at the time of the waiver. However, no repayment will be made more than three years after the date of a payment or waiver.

Pursuant to this agreement, less than $1,000 of expenses were waived/paid by Price Associates during the year ended May 31, 2017 and remain subject to repayment by the fund.

In addition, the fund has entered into service agreements with Price Associates and two wholly owned subsidiaries of Price Associates (collectively, Price). Price Associates provides certain accounting and administrative services to the fund. T. Rowe Price Services, Inc. provides shareholder and administrative services in its capacity as the fund’s transfer and dividend-disbursing agent. T. Rowe Price Retirement Plan Services, Inc. provides subaccounting and recordkeeping services for certain retirement accounts invested in the Investor Class and I Class. For the year ended May 31, 2017, expenses incurred pursuant to these service agreements were $81,000 for Price Associates; $596,000 for T. Rowe Price Services, Inc.; and $154,000 for T. Rowe Price Retirement Plan Services, Inc. The total amount payable at period-end pursuant to these service agreements is reflected as Due to Affiliates in the accompanying financial statements.

The fund is also one of several mutual funds sponsored by Price Associates (underlying Price funds) in which the T. Rowe Price Spectrum Funds (Spectrum Funds) may invest. The Spectrum Funds do not invest in the underlying Price funds for the purpose of exercising management or control. Pursuant to a special servicing agreement, expenses associated with the operation of the Spectrum Funds are borne by each underlying Price fund to the extent of estimated savings to it and in proportion to the average daily value of its shares owned by the Spectrum Funds. Expenses allocated under this agreement are reflected as shareholder servicing expense in the accompanying financial statements. For the year ended May 31, 2017, the fund was allocated $715,000 of Spectrum Funds’ expenses. Of these amounts, $486,000 related to services provided by Price. At period-end, the amount payable to Price pursuant to this agreement is reflected as Due to Affiliates in the accompanying financial statements. At May 31, 2017, approximately 39% of the outstanding shares of the Investor Class were held by the Spectrum Funds.

The fund may invest in the T. Rowe Price Government Reserve Fund, the T. Rowe Price Treasury Reserve Fund, or the T. Rowe Price Short-Term Fund (collectively, the Price Reserve Funds), open-end management investment companies managed by Price Associates and considered affiliates of the fund. The Price Reserve Funds are offered as short-term investment options to mutual funds, trusts, and other accounts managed by Price Associates or its affiliates and are not available for direct purchase by members of the public. The Price Reserve Funds pay no investment management fees.

The fund may participate in securities purchase and sale transactions with other funds or accounts advised by Price Associates (cross trades), in accordance with procedures adopted by the fund’s Board and Securities and Exchange Commission rules, which require, among other things, that such purchase and sale cross trades be effected at the independent current market price of the security. During the year ended May 31, 2017, the fund had no purchases or sales cross trades with other funds or accounts advised by Price Associates.

In our opinion, the accompanying statement of assets and liabilities, including the portfolio of investments, and the related statements of operations and of changes in net assets and the financial highlights present fairly, in all material respects, the financial position of the T. Rowe Price GNMA Fund (the “Fund”) as of May 31, 2017, 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 the financial highlights for each of the periods indicated therein, in conformity with accounting principles generally accepted in the United States of America. These financial statements and financial highlights (hereafter referred to as “financial statements”) are the responsibility of the Fund’s management. Our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these financial statements in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits, which included confirmation of securities as of May 31, 2017 by correspondence with the custodian and brokers, and confirmation of the underlying fund by correspondence with the transfer agent, provide a reasonable basis for our opinion.

We are providing this information as required by the Internal Revenue Code. The amounts shown may differ from those elsewhere in this report because of differences between tax and financial reporting requirements.

The fund’s distributions to shareholders included $8,000 from short-term capital gains.

A description of the policies and procedures used by T. Rowe Price funds and portfolios to determine how to vote proxies relating to portfolio securities is available in each fund’s Statement of Additional Information. You may request this document by calling 1-800-225-5132 or by accessing the SEC’s website, sec.gov.

The description of our proxy voting policies and procedures is also available on our corporate website. To access it, please visit the following Web page:

Scroll down to the section near the bottom of the page that says, “Proxy Voting Policies.” Click on the Proxy Voting Policies link in the shaded box.

Each fund’s most recent annual proxy voting record is available on our website and through the SEC’s website. To access it through T. Rowe Price, visit the website location shown above, and scroll down to the section near the bottom of the page that says, “Proxy Voting Records.” Click on the Proxy Voting Records link in the shaded box.

The fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year on Form N-Q. The fund’s Form N-Q is available electronically on the SEC’s website (sec.gov); hard copies may be reviewed and copied at the SEC’s Public Reference Room, 100 F St. N.E., Washington, DC 20549. For more information on the Public Reference Room, call 1-800-SEC-0330.

Each year, the fund’s Board of Trustees (Board) considers the continuation of the investment management agreement (Advisory Contract) between the fund and its investment advisor, T. Rowe Price Associates, Inc. (Advisor). In that regard, at an in-person meeting held on March 6–7, 2017 (Meeting), the Board, including a majority of the fund’s independent trustees, approved the continuation of the fund’s Advisory Contract. At the Meeting, the Board considered the factors and reached the conclusions described below relating to the selection of the Advisor and the approval of the Advisory Contract. The independent trustees were assisted in their evaluation of the Advisory Contract by independent legal counsel from whom they received separate legal advice and with whom they met separately.

In providing information to the Board, the Advisor was guided by a detailed set of requests for information submitted by independent legal counsel on behalf of the independent trustees. In considering and approving the Advisory Contract, the Board considered the information it believed was relevant, including, but not limited to, the information discussed below. The Board considered not only the specific information presented in connection with the Meeting but also the knowledge gained over time through interaction with the Advisor about various topics. The Board meets regularly and, at each of its meetings, covers an extensive agenda of topics and materials and considers factors that are relevant to its annual consideration of the renewal of the T. Rowe Price funds’ advisory contracts, including performance and the services and support provided to the funds and their shareholders.

Services Provided by the Advisor
The Board considered the nature, quality, and extent of the services provided to the fund by the Advisor. These services included, but were not limited to, directing the fund’s investments in accordance with its investment program and the overall management of the fund’s portfolio, as well as a variety of related activities such as financial, investment operations, and administrative services; compliance; maintaining the fund’s records and registrations; and shareholder communications. The Board also reviewed the background and experience of the Advisor’s senior management team and investment personnel involved in the management of the fund, as well as the Advisor’s compliance record. The Board concluded that it was satisfied with the nature, quality, and extent of the services provided by the Advisor.

Investment Performance of the Fund
The Board took into account discussions with the Advisor and reports that it receives throughout the year relating to fund performance. In connection with the Meeting, the Board reviewed the fund’s net annualized total returns for the 1-, 2-, 3-, 4-, 5-, and 10-year periods as of September 30, 2016, and compared these returns with the performance of a peer group of funds with similar investment programs and a wide variety of other previously agreed-upon comparable performance measures and market data, including those supplied by Broadridge, which is an independent provider of mutual fund data.

On the basis of this evaluation and the Board’s ongoing review of investment results, and factoring in the relative market conditions during certain of the performance periods, the Board concluded that the fund’s performance was satisfactory.

Costs, Benefits, Profits, and Economies of Scale
The Board reviewed detailed information regarding the revenues received by the Advisor under the Advisory Contract and other benefits that the Advisor (and its affiliates) may have realized from its relationship with the fund, including any research received under “soft dollar” agreements and commission-sharing arrangements with broker-dealers. The Board considered that the Advisor may receive some benefit from soft-dollar arrangements pursuant to which research is received from broker-dealers that execute the fund’s portfolio transactions. The Board received information on the estimated costs incurred and profits realized by the Advisor from managing the T. Rowe Price funds. The Board also reviewed estimates of the profits realized from managing the fund in particular, and the Board concluded that the Advisor’s profits were reasonable in light of the services provided to the fund.

The Board also considered whether the fund benefits under the fee levels set forth in the Advisory Contract from any economies of scale realized by the Advisor. Under the Advisory Contract, the fund pays a fee to the Advisor for investment management services composed of two components—a group fee rate based on the combined average net assets of most of the T. Rowe Price funds (including the fund) that declines at certain asset levels and an individual fund fee rate based on the fund’s average daily net assets—and the fund pays its own expenses of operations (subject to an expense limitation agreed to by the Advisor with respect to the fund’s I Class). At the Meeting, the Board approved an additional 0.005% breakpoint to the group fee schedule, effective May 1, 2017. With the new breakpoint, the group fee rate will decline to 0.265% when the combined average net assets of the applicable T. Rowe Price funds exceed $650 billion. The Board concluded that the advisory fee structure for the fund continued to provide for a reasonable sharing of benefits from any economies of scale with the fund’s investors.

Fees and Expenses
The Board was provided with information regarding industry trends in management fees and expenses. Among other things, the Board reviewed data for peer groups that were compiled by Broadridge, which compared: (i) contractual management fees, total expenses, actual management fees, and non-management expenses of the Investor Class of the fund to a group of competitor funds selected by Broadridge (Expense Group) and (ii) total expenses, actual management fees, and non-management expenses of the Investor Class of the fund to a broader set of funds within the Lipper investment classification (Expense Universe). The Board considered the fund’s contractual management fee rate, actual management fee rate (which reflects the management fees actually received from the fund by the Advisor after any applicable waivers, reductions, or reimbursements), operating expenses, and total expenses (which reflects the net total expense ratio of the fund after any waivers, reductions, or reimbursements) in comparison with the information for the Broadridge peer groups. Broadridge generally constructed the peer groups by seeking the most comparable funds based on similar investment classifications and objectives, expense structure, asset size, and operating components and attributes and ranked funds into quintiles, with the first quintile representing the funds with the lowest relative expenses and the fifth quintile representing the funds with the highest relative expenses. The information provided to the Board indicated that the fund’s contractual management fee ranked in the second quintile (Expense Group), the fund’s actual management fee rate ranked in the second quintile (Expense Group) and third quintile (Expense Universe), and the fund’s total expenses ranked in the first quintile (Expense Group) and second and third quintiles (Expense Universe).

The Board also reviewed the fee schedules for institutional accounts and private accounts with similar mandates that are advised or subadvised by the Advisor and its affiliates. Management provided the Board with information about the Advisor’s responsibilities and services provided to subadvisory and other institutional account clients, including information about how the requirements and economics of the institutional business are fundamentally different from those of the mutual fund business. The Board considered information showing that the Advisor’s mutual fund business is generally more complex from a business and compliance perspective than its institutional account business and considered various relevant factors, such as the broader scope of operations and oversight, more extensive shareholder communication infrastructure, greater asset flows, heightened business risks, and differences in applicable laws and regulations associated with the Advisor’s proprietary mutual fund business. In assessing the reasonableness of the fund’s management fee rate, the Board considered the differences in the nature of the services required for the Advisor to manage its mutual fund business versus managing a discrete pool of assets as a subadvisor to another institution’s mutual fund or for an institutional account and that the Advisor generally performs significant additional services and assumes greater risk in managing the fund and other T. Rowe Price funds than it does for institutional account clients.

On the basis of the information provided and the factors considered, the Board concluded that the fees paid by the fund under the Advisory Contract are reasonable.

Approval of the Advisory Contract
As noted, the Board approved the continuation of the Advisory Contract. No single factor was considered in isolation or to be determinative to the decision. Rather, the Board concluded, in light of a weighting and balancing of all factors considered, that it was in the best interests of the fund and its shareholders for the Board to approve the continuation of the Advisory Contract (including the fees to be charged for services thereunder).

Your fund is overseen by a Board of Trustees (Board) that meets regularly to review a wide variety of matters affecting or potentially affecting the fund, including performance, investment programs, compliance matters, advisory fees and expenses, service providers, and business and regulatory affairs. The Board elects the fund’s officers, who are listed in the final table. At least 75% of the Board’s members are independent of T. Rowe Price Associates, Inc. (T. Rowe Price), and its affiliates; “inside” or “interested” Trustees are employees or officers of T. Rowe Price. The business address of each director and officer is 100 East Pratt Street, Baltimore, Maryland 21202. The Statement of Additional Information includes additional information about the fund Trustees and is available without charge by calling a T. Rowe Price representative at 1-800-638-5660.

The registrant has adopted a code of ethics, as defined in Item 2 of Form N-CSR, applicable to its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A copy of this code of ethics is filed as an exhibit to this Form N-CSR. No substantive amendments were approved or waivers were granted to this code of ethics during the period covered by this report.

The registrant’s Board of Directors/Trustees has determined that Mr. Bruce W. Duncan qualifies as an audit committee financial expert, as defined in Item 3 of Form N-CSR. Mr. Duncan is considered independent for purposes of Item 3 of Form N-CSR.

(a) – (d) Aggregate fees billed for the last two fiscal years for professional services rendered to, or on behalf of, the registrant by the registrant’s principal accountant were as follows:

Audit fees include amounts related to the audit of the registrant’s annual financial statements and services normally provided by the accountant in connection with statutory and regulatory filings. Audit-related fees include amounts reasonably related to the performance of the audit of the registrant’s financial statements and specifically include the issuance of a report on internal controls and, if applicable, agreed-upon procedures related to fund acquisitions. Tax fees include amounts related to services for tax compliance, tax planning, and tax advice. The nature of these services specifically includes the review of distribution calculations and the preparation of Federal, state, and excise tax returns. All other fees include the registrant’s pro-rata share of amounts for agreed-upon procedures in conjunction with service contract approvals by the registrant’s Board of Directors/Trustees.

(e)(1) The registrant’s audit committee has adopted a policy whereby audit and non-audit services performed by the registrant’s principal accountant for the registrant, its investment adviser, and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant require pre-approval in advance at regularly scheduled audit committee meetings. If such a service is required between regularly scheduled audit committee meetings, pre-approval may be authorized by one audit committee member with ratification at the next scheduled audit committee meeting. Waiver of pre-approval for audit or non-audit services requiring fees of a de minimis amount is not permitted.

(2) No services included in (b) – (d) above were approved pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

(f) Less than 50 percent of the hours expended on the principal accountant’s engagement to audit the registrant’s financial statements for the most recent fiscal year were attributed to work performed by persons other than the principal accountant’s full-time, permanent employees.

(g) The aggregate fees billed for the most recent fiscal year and the preceding fiscal year by the registrant’s principal accountant for non-audit services rendered to the registrant, its investment adviser, and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant were $1,765,000 and $2,409,000, respectively.

(h) All non-audit services rendered in (g) above were pre-approved by the registrant’s audit committee. Accordingly, these services were considered by the registrant’s audit committee in maintaining the principal accountant’s independence.

(a) Not applicable. The complete schedule of investments is included in Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

(a) The registrant’s principal executive officer and principal financial officer have evaluated the registrant’s disclosure controls and procedures within 90 days of this filing and have concluded that the registrant’s disclosure controls and procedures were effective, as of that date, in ensuring that information required to be disclosed by the registrant in this Form N-CSR was recorded, processed, summarized, and reported timely.

(b) The registrant’s principal executive officer and principal financial officer are aware of no change in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

(a)(1) The registrant’s code of ethics pursuant to Item 2 of Form N-CSR is attached.

(2) Separate certifications by the registrant's principal executive officer and principal financial officer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 and required by Rule 30a-2(a) under the Investment Company Act of 1940, are attached.

(3) Written solicitation to repurchase securities issued by closed-end companies: not applicable.

(b) A certification by the registrant's principal executive officer and principal financial officer, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and required by Rule 30a-2(b) under the Investment Company Act of 1940, is attached.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

T. Rowe Price GNMA Fund

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

		By	/s/ Edward C. Bernard
			Edward C. Bernard
			Principal Executive Officer

Date	July 18, 2017


		By	/s/ Catherine D. Mathews
			Catherine D. Mathews
			Principal Financial Officer

Date	July 18, 2017

Independent Trustees

Name
(Year of Birth)
Year Elected*
[Number of T. Rowe Price		Principal Occupation(s) and Directorships of Public Companies and
Portfolios Overseen]		Other Investment Companies During the Past Five Years

Anthony W. Deering		Chairman, Exeter Capital, LLC, a private investment firm (2004 to
(1945)		present); Director and Advisory Board Member, Deutsche Bank North
1985		America (2004 to present); Director, Vornado Real Estate Investment
[189]		Trust (2004 to 2012); Director, Under Armour (2008 to present);
		Director, Brixmor Real Estate Investment Trust (2012 to present)

Bruce W. Duncan		Chief Executive Officer and Director (2009 to December 2016),
(1951)		Chairman of the Board (January 2016 to present), and President
2013		(2009 to September 2016), First Industrial Realty Trust, an owner
[189]		and operator of industrial properties; Chairman of the Board
		(2005 to September 2016) and Director (1999 to September
		2016), Starwood Hotels & Resorts, a hotel and leisure company;
		Director, Boston Properties (May 2016 to present); Director, Marriott
		International, Inc. (September 2016 to present)

Robert J. Gerrard, Jr.		Advisory Board Member, Pipeline Crisis/Winning Strategies, a
(1952)		collaborative working to improve opportunities for young African
2013		Americans (1997 to present)
[189]

Paul F. McBride		Advisory Board Member, Vizzia Technologies (2015 to present)
(1956)
2013
[189]

Cecilia E. Rouse, Ph.D.		Dean, Woodrow Wilson School (2012 to present); Professor and
(1963)		Researcher, Princeton University (1992 to present); Member of
2013		National Academy of Education (2010 to present); Director, MDRC,
[189]		a nonprofit education and social policy research organization
		(2011 to present); Research Associate of Labor Studies Program
		(2011 to 2015) and Board Member (2015 to present), National
		Bureau of Economic Research (2011 to present); Chair of Committee
		on the Status of Minority Groups in the Economic Profession
		(2012 to present); Vice President (2015 to present), American
		Economic Association

John G. Schreiber		Owner/President, Centaur Capital Partners, Inc., a real estate
(1946)		investment company (1991 to present); Cofounder, Partner, and
1992		Cochairman of the Investment Committee, Blackstone Real Estate
[189]		Advisors, L.P. (1992 to 2015); Director, General Growth Properties,
		Inc. (2010 to 2013); Director, Blackstone Mortgage Trust, a real
		estate finance company (2012 to 2016); Director and Chairman of
		the Board, Brixmor Property Group, Inc. (2013 to present); Director,
		Hilton Worldwide (2013 to present); Director, Hudson Pacific
		Properties (2014 to 2016)

Mark R. Tercek		President and Chief Executive Officer, The Nature Conservancy (2008
(1957)		to present)
2009
[189]

*Each independent trustee serves until retirement, resignation, or election of a successor.

Inside Trustees

Name
(Year of Birth)
Year Elected*
[Number of T. Rowe Price		Principal Occupation(s) and Directorships of Public Companies and
Portfolios Overseen]		Other Investment Companies During the Past Five Years

Edward C. Bernard		Director and Vice President, T. Rowe Price; Vice Chairman of the
(1956)		Board, Director, and Vice President, T. Rowe Price Group, Inc.;
2006		Chairman of the Board, Director, and Vice President, T. Rowe Price
[189]		Investment Services, Inc., and T. Rowe Price Services, Inc.; Chairman
		of the Board and Director, T. Rowe Price Retirement Plan Services,
		Inc.; Chairman of the Board, Chief Executive Officer, Director, and
		President, T. Rowe Price International and T. Rowe Price Trust
		Company; Chairman of the Board, all funds

Edward A. Wiese, CFA		Vice President, T. Rowe Price, T. Rowe Price Group, Inc., T. Rowe
(1959)		Price International, and T. Rowe Price Trust Company
2015
[57]

*Each inside trustee serves until retirement, resignation, or election of a successor.

Officers

Name (Year of Birth)
Position Held With GNMA Fund		Principal Occupation(s)

Anil K. Andhavarapu (1980)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Darrell N. Braman (1963)		Vice President, Price Hong Kong, Price
Vice President and Secretary		Singapore, T. Rowe Price, T. Rowe Price Group,
		Inc., T. Rowe Price International, T. Rowe Price
		Investment Services, Inc., and T. Rowe Price
		Services, Inc.

Brian J. Brennan, CFA (1964)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., T. Rowe Price International, and
		T. Rowe Price Trust Company

Christopher P. Brown, Jr., CFA (1977)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Ramon R. de Castro (1966)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

John R. Gilner (1961)		Chief Compliance Officer and Vice President,
Chief Compliance Officer		T. Rowe Price; Vice President, T. Rowe Price
		Group, Inc., and T. Rowe Price Investment
		Services, Inc.

Keir R. Joyce, CFA (1972)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Steven M. Kohlenstein (1987)		Vice President, T. Rowe Price
Vice President

Paul J. Krug, CPA (1964)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company

Martin G. Lee (1963)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Alan D. Levenson, Ph.D. (1958)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Catherine D. Mathews (1963)		Vice President, T. Rowe Price, T. Rowe Price
Treasurer and Vice President		Group, Inc., and T. Rowe Price Trust Company

Andrew C. McCormick (1960)		Vice President, T. Rowe Price, T. Rowe Price
President		Group, Inc., and T. Rowe Price Trust Company

David Oestreicher (1967)		Director, Vice President, and Secretary, T. Rowe
Vice President		Price Investment Services, Inc., T. Rowe
		Price Retirement Plan Services, Inc., T. Rowe
		Price Services, Inc., and T. Rowe Price Trust
		Company; Chief Legal Officer, Vice President,
		and Secretary, T. Rowe Price Group, Inc.; Vice
		President and Secretary, T. Rowe Price and
		T. Rowe Price International; Vice President,
		Price Hong Kong and Price Singapore

John W. Ratzesberger (1975)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company;
		formerly, North American Head of Listed
		Derivatives Operation, Morgan Stanley
		(to 2013)

Shannon H. Rauser (1987)		Employee, T. Rowe Price
Assistant Secretary

Deborah D. Seidel (1962)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., T. Rowe Price Investment Services,
		Inc., and T. Rowe Price Services, Inc.

Michael K. Sewell (1982)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Victor M. Weinblatt (1988)		Assistant Vice President, T. Rowe Price;
Assistant Vice President		formerly, Financial Software Developer,
		Bloomberg L.P. (to 2014)

John D. Wells (1960)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Rick Zhang, CFA (1984)		Vice President, T. Rowe Price
Vice President

Unless otherwise noted, officers have been employees of T. Rowe Price or T. Rowe Price International for at least 5 years.

/s/ Edward C. Bernard

Edward C. Bernard

Principal Executive Officer

July 18, 2017