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

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act File Number: 811-05986

T. Rowe Price Index Trust, Inc.

(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: December 31

Date of reporting period: March 31, 2018

T. Rowe Price Index Trust, Inc. (the corporation) is registered under the Investment Company Act of 1940 (the 1940 Act). The Extended Equity Market Index Fund (the fund) is a diversified, open-end management investment company established by the corporation. The fund seeks to track the performance of a benchmark index that measures the investment return of small- and mid-capitalization U.S. stocks.

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 Portfolio of Investments was 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 Portfolio of Investments may differ from the values ultimately realized upon sale or maturity.

Investment Transactions
Investment transactions are accounted for on the trade date basis.

New Accounting Guidance
In March 2017, the FASB issued amended guidance to shorten the amortization period for certain callable debt securities, held at a premium. The guidance is effective for fiscal years and interim periods beginning after December 15, 2018. Adoption will have no effect on the fund’s net assets or results of operations.

Indemnification
In the normal course of business, the fund may provide indemnification in connection with its officers and directors, service providers, and/or private company investments. The fund’s maximum exposure under these arrangements is unknown; however, the risk of material loss is currently considered to be remote.

The fund’s financial instruments are valued and its 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 Directors (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
Equity securities listed or regularly traded on a securities exchange or in the over-the-counter (OTC) market are valued at the last quoted sale price or, for certain markets, the official closing price at the time the valuations are made. OTC Bulletin Board securities are valued at the mean of the closing bid and asked prices. A security that is listed or traded on more than one exchange is valued at the quotation on the exchange determined to be the primary market for such security. Listed securities not traded on a particular day are valued at the mean of the closing bid and asked prices. Actively traded equity securities listed on a domestic exchange generally are categorized in Level 1 of the fair value hierarchy. OTC Bulletin Board securities, certain preferred securities, and equity securities traded in inactive markets generally are categorized in Level 2 of the fair value hierarchy.

Debt securities generally are traded in the OTC market. Debt 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.

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 an equity investment with limited market activity, such as a private placement or a thinly traded public company stock, 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, new rounds of financing, negotiated transactions of significant size between other investors in the company, relevant market valuations of peer companies, 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 market-based valuation multiples; a discount or premium from market value of a similar, freely traded security of the same issuer; 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 March 31, 2018:

There were no material transfers between Levels 1 and 2 during the period ended March 31, 2018.

Following is a reconciliation of the fund’s Level 3 holdings for the period ended March 31, 2018. Gain (loss) reflects both realized and change in unrealized gain/loss on Level 3 holdings during the period, if any. The change in unrealized gain/loss on Level 3 instruments held at March 31, 2018, totaled $0 for the period ended March 31, 2018.

The fund may invest 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 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, as described in Note 2.

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; securities posted by the fund are so noted in the accompanying Portfolio of Investments. As of March 31, 2018, securities valued at $1,381,000 had been posted by the fund for exchange-traded and/or centrally cleared derivatives.

While typically not sold in the same manner as equity or fixed income securities, exchange-traded or centrally cleared derivatives may be closed out only on the exchange or clearinghouse where the contracts were traded. This ability is subject to the liquidity of underlying positions.

Futures Contracts
The fund may enter into futures contracts as an efficient means of maintaining liquidity while being invested in the market, to facilitate trading, or to reduce transaction costs. 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. 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, interest rates, or currency values; and potential losses in excess of the fund’s initial investment.

Consistent with its investment objective, the fund engages in the following practices to manage exposure to certain risks 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.

Securities Lending
The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities, collateral investments decline in value, and the lending agent fails to perform. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying Portfolio of Investments, but collateral received in the form of securities is not. At March 31, 2018, the value of loaned securities was $143,871,000; the value of cash collateral and related investments was $146,070,000.

The fund may invest its cash reserves in certain open-end management investment companies managed by T. Rowe Price Associates, Inc. (Price Associates) and considered affiliates of the fund: the T. Rowe Price Government Reserve Fund or the T. Rowe Price Treasury Reserve Fund, organized as money market funds, or the T. Rowe Price Short-Term Fund, a short-term bond fund (collectively, the Price Reserve Funds). 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. Cash collateral from securities lending is invested in the T. Rowe Price Short-Term Fund. The Price Reserve Funds pay no investment management fees.

T. Rowe Price Index Trust, Inc. (the corporation) is registered under the Investment Company Act of 1940 (the 1940 Act). The Total Equity Market Index Fund (the fund) is a diversified, open-end management investment company established by the corporation. The fund seeks to match the performance of the entire U.S. stock market, as represented by the S&P Total Market Index.

Investment Transactions
Investment transactions are accounted for on the trade date basis.

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

Valuation Inputs
The following table summarizes the fund’s financial instruments, based on the inputs used to determine their fair values on March 31, 2018:

There were no material transfers between Levels 1 and 2 during the period ended March 31, 2018.

Collateral may be in the form of cash or debt securities issued by the U.S. government or related agencies; securities posted by the fund are so noted in the accompanying Portfolio of Investments. As of March 31, 2018, securities valued at $2,293,000 had been posted by the fund for exchange-traded and/or centrally cleared derivatives.

Securities Lending
The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities, collateral investments decline in value, and the lending agent fails to perform. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying Portfolio of Investments, but collateral received in the form of securities is not. At March 31, 2018, the value of loaned securities was $48,849,000; the value of cash collateral and related investments was $50,479,000.

T. Rowe Price Index Trust, Inc. (the corporation) is registered under the Investment Company Act of 1940 (the 1940 Act). The Equity Index 500 Fund (the fund) is a diversified, open-end management investment company established by the corporation. The fund seeks to track the performance of a benchmark index that measures the investment return of large-capitalization U.S. stocks.

Investment Transactions
Investment transactions are accounted for on the trade date basis.

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.

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

Valuation Inputs
The following table summarizes the fund’s financial instruments, based on the inputs used to determine their fair values on March 31, 2018:

There were no material transfers between Levels 1 and 2 during the period ended March 31, 2018.

Collateral may be in the form of cash or debt securities issued by the U.S. government or related agencies; securities posted by the fund are so noted in the accompanying Portfolio of Investments. As of March 31, 2018, securities valued at $2,748,000 had been posted by the fund for exchange-traded and/or centrally cleared derivatives.

Securities Lending
The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities, collateral investments decline in value, and the lending agent fails to perform. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying Portfolio of Investments, but collateral received in the form of securities is not. At March 31, 2018, the value of loaned securities was $361,622,000; the value of cash collateral and related investments was $366,529,000.

Consistent with its investment objective, the fund may invest in T. Rowe Price Group, Inc. Additionally, the fund may invest its cash reserves in certain open-end management investment companies managed by T. Rowe Price Associates, Inc. (Price Associates) and considered affiliates of the fund: the T. Rowe Price Government Reserve Fund or the T. Rowe Price Treasury Reserve Fund, organized as money market funds, or the T. Rowe Price Short-Term Fund, a short-term bond fund (collectively, the Price Reserve Funds). 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. Cash collateral from securities lending is invested in the T. Rowe Price Short-Term Fund. The Price Reserve Funds pay no investment management fees.

T. Rowe Price Index Trust, Inc. (the corporation) is registered under the Investment Company Act of 1940 (the 1940 Act). The Mid-Cap Index Fund (the fund) is a diversified, open-end management investment company established by the corporation. The fund is available for investment only by mutual funds, college savings plans, and other institutional client accounts managed by T. Rowe Price Associates, Inc., or its affiliates and is not available for direct purchase by members of the public. The fund seeks to track the performance of a benchmark index that measures the investment return of mid-capitalization U.S. stocks.

Investment Transactions
Investment transactions are accounted for on the trade date basis.

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

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.

Valuation Inputs
On March 31, 2018, all of the fund’s financial instruments were classified as Level 1, based on the inputs used to determine their fair values. There were no material transfers between Levels 1 and 2 during the period ended March 31, 2018.

Securities Lending
The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities, collateral investments decline in value, and the lending agent fails to perform. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying Portfolio of Investments, but collateral received in the form of securities is not. At March 31, 2018, the value of loaned securities was $626,000; the value of cash collateral and related investments was $635,000.

T. Rowe Price Index Trust, Inc. (the corporation) is registered under the Investment Company Act of 1940 (the 1940 Act). The Small-Cap Index Fund (the fund) is a diversified, open-end management investment company established by the corporation. The fund is available for investment only by mutual funds, college savings plans, and other institutional client accounts managed by T. Rowe Price Associates, Inc., or its affiliates and is not available for direct purchase by members of the public. The fund seeks to track the performance of a benchmark index that measures the investment return of small-capitalization U.S. stocks.

Investment Transactions
Investment transactions are accounted for on the trade date basis.

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

Valuation Inputs
The following table summarizes the fund’s financial instruments, based on the inputs used to determine their fair values on March 31, 2018:

There were no material transfers between Levels 1 and 2 during the period ended March 31, 2018.

Collateral may be in the form of cash or debt securities issued by the U.S. government or related agencies; securities posted by the fund are so noted in the accompanying Portfolio of Investments. As of March 31, 2018, securities valued at $58,000 had been posted by the fund for exchange-traded and/or centrally cleared derivatives.

Securities Lending
The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities, collateral investments decline in value, and the lending agent fails to perform. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying Portfolio of Investments, but collateral received in the form of securities is not. At March 31, 2018, the value of loaned securities was $847,000; the value of cash collateral and related investments was $860,000.

(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-Q 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 most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

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.

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 Index Trust, Inc.

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

Date May 24, 2018

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 May 24, 2018


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

Date May 24, 2018