Blackrock Index Funds Inc.

05/05/2026 | Press release | Distributed by Public on 05/05/2026 11:52

Summary Prospectus by Investment Company (Form 497K)

APRIL 30, 2026 
 
 
Summary Prospectus
BlackRock Index Funds, Inc. | Class K Shares
●
iShares Russell 2000 Small-Cap Index Fund
Class K: BDBKX
Before you invest, you may want to review the Fund's prospectus, which contains more information about the Fund and its risks. You can find the Fund's prospectus (including amendments and supplements), reports to shareholders and other information about the Fund, including the Fund's statement of additional information, online at https://www.blackrock.com/prospectus. You can also get this information at no cost by calling (800) 537-4942 or by sending an e-mail request to [email protected], or from your financial professional. The Fund's prospectus and statement of additional information, both dated April 30, 2026, as amended and supplemented from time to time, are incorporated by reference into (legally made a part of) this Summary Prospectus.
This Summary Prospectus contains information you should know before investing, including information about risks. Please read it before you invest and keep it for future reference.
The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this Summary Prospectus. Any representation to the contrary is a criminal offense.
Not FDIC Insured ● May Lose Value ● No Bank Guarantee
Summary Prospectus
Key Facts About iShares Russell 2000 Small-Cap Index Fund
Investment Objective
The investment objective of iShares Russell 2000 Small-Cap Index Fund ("Russell 2000 Small-Cap Index Fund"or the "Fund"), a series of BlackRock Index Funds, Inc. (the "Corporation"), is to match the performance of the Russell 2000® Index (the "Russell 2000" or the "Underlying Index") as closely as possible before the deduction of Fund expenses.
Fees and Expenses of the Fund
This table describes the fees and expenses that you may pay if you buy, hold and sell Class K Shares of Russell 2000 Small-Cap Index Fund. You may pay other fees, such as brokerage commissions and other fees to your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock Advisors, LLC ("BlackRock") and its affiliates) (each, a "Financial Intermediary"), which are not reflected in the table and example below. 
Annual Fund Operating Expenses
(expenses that you pay each year as a
percentage of the value of your investment)
Class K
Shares
Management Fee1,2
0.01%
Distribution and/or Service (12b-1) Fees
None
Other Expenses
0.06%
Administration Fees
0.04%
Miscellaneous Other Expenses
0.02%
Total Annual Fund Operating Expenses
0.07%
Fee Waivers and/or Expense Reimbursements2,3
-
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements2,3
0.07%
 
1
The fees and expenses shown in the table and the example that follows include both the expenses of Russell 2000 Small-Cap Index Fund and Russell 2000 Small-Cap Index Fund's share of the allocated expenses of Master Small Cap Index Series (the "Series"), a series of Quantitative Master Series LLC (the "Master LLC"). The management fees are paid by the Series.
2
As described in the "Management of the Funds" section of the Fund's prospectus beginning on page 36, BlackRock has contractually agreed to waive the management fee with respect to any portion of the Series' assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BlackRock or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BlackRock has contractually agreed to waive its management fees by the amount of investment advisory fees the Series pays to BlackRock indirectly through its investment in money market funds managed by BlackRock or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days' notice by a majority of the non-interested directors of the Master LLC or by a vote of a majority of the outstanding voting securities of the Series.
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As described in the "Management of the Funds" section of the Fund's prospectus beginning on page 36, BlackRock has contractually agreed to waive and/or reimburse fees and/or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of Russell 2000 Small-Cap Index Fund (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.07% (for Class K Shares) of average daily net assets through June 30, 2027. In addition to the contractual waiver with respect to the Fund, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of the Series (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Series expenses) to 0.07% of average daily net assets through June 30, 2027. These contractual agreements may be terminated upon 90 days' notice by a majority of the non-interested directors of the Corporation or of the Master LLC, as applicable, or by a vote of a majority of the outstanding voting securities of the Fund or the Series, as applicable.
Example:
This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be: 
1 Year
3 Years
5 Years
10 Years
Class K Shares
$7
$23
$40
$90
 
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Portfolio Turnover:
The Series pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Series' portfolio turnover rate was 21% of the average value of its portfolio.
Principal Investment Strategies of the Fund
Russell 2000 Small-Cap Index Fund employs a "passive" management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Russell 2000. The Fund will be substantially invested in securities in the Russell 2000, and will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in the Russell 2000. The Fund may change its target index if Fund management believes a different index would better enable the Fund to match the performance of the market segment represented by the current index.
The Fund may invest in a statistically selected sample of stocks included in the Russell 2000 and in derivative instruments linked to the Russell 2000. The Fund may not invest in all of the common stocks in the Russell 2000, or in the same weightings as in the Russell 2000. The Fund chooses investments so that the market capitalizations, industry weightings and other fundamental characteristics of the stocks and derivative instruments chosen are similar to the Russell 2000 as a whole. As of March 31, 2026, the companies in the Russell 2000 have a market capitalization ranging from $3.29 million to $39.25 billion.
The Fund is a "feeder" fund that invests all of its assets in the Series, a series of the Master LLC, which has the same investment objective and strategies as the Fund. All investments are made at the Series level. This structure is sometimes called a "master/feeder" structure. The Fund's investment results will correspond directly to the investment results of the Series. For simplicity, this prospectus uses the name of the Fund or the term "Fund" (as applicable) to include the Series.
Principal Risks of Investing in the Fund
Risk is inherent in all investing. The value of your investment in Russell 2000 Small-Cap Index Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other Government agency. The following is a summary description of the principal risks of investing in the Fund. The relative significance of each risk factor below may change over time and you should review each risk factor carefully.
◼
Small Cap Securities Risk - Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
◼
Index-Related Risk - The index provider may rely on various sources of information to assess the criteria of components of the Underlying Index, including information that may be based on assumptions and estimates. Neither the Fund nor BlackRock can offer assurances that the index provider's methodology or sources of information will provide an accurate assessment of included components. Errors in index data, index computations or the construction of the Underlying Index in accordance with its methodology may occur, and the index provider may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to postpone a scheduled rebalance. This could cause the Underlying Index to vary from its normal or expected composition.
◼
Passive Investment Risk - Because BlackRock does not select individual companies in the index that the Fund tracks, the Fund may hold securities of companies that present risks that an investment adviser researching individual securities might seek to avoid.
◼
Tracking Error Risk - The Fund is subject to the risk of "tracking error," which is the divergence of the Fund's performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including differences between the securities and other assets held in the Fund's portfolio and those included in the
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Underlying Index; differences in the timing and methodologies used to value securities and other assets; transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund's holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or timing of withholding taxes on dividends reflected in the Underlying Index from the Fund's obligation, if any, for foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened during times of increased market volatility or other unusual market conditions.
◼
Equity Securities Risk - Stock markets are volatile. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions.
◼
Market Risk and Selection Risk - Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a security or other asset may decline due to changes in general market conditions, economic trends or events that are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its investments. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.
◼
Operational and Technology Risks - The Fund is directly and indirectly susceptible to operational and technology risks, including those related to human errors, processing errors, communication errors, systems failures, cybersecurity incidents, and the use of artificial intelligence and machine learning ("AI"), which may result in losses for the Fund and its shareholders or may impair the Fund's operations. While the Fund's service providers are required to have appropriate operational, information security and cybersecurity risk management policies and procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and may cause the Fund's investments in such issuers to lose value.
◼
Representative Sampling Risk - Representative sampling is a method of indexing that involves investing in a representative sample of securities that collectively have a similar investment profile to the Underlying Index and resemble the Underlying Index in terms of risk factors and other key characteristics. The Fund may or may not hold every security in the Underlying Index. When the Fund deviates from a full replication indexing strategy to utilize a representative sampling strategy, the Fund is subject to an increased risk of tracking error, in that the securities selected in the aggregate for the Fund may not have an investment profile similar to those of the Underlying Index.
◼
Risk of Investing in the United States - Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
Performance Information
The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund's performance to that of the Russell 3000® Index and the Russell 2000. The Russell 2000 is relevant to the Fund because it has characteristics similar to the Fund's investment strategy. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If the Fund's investment manager and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund's returns would have been lower. Updated information on the Fund's performance, including its current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at (800) 882-0052.
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Class K Shares
ANNUAL TOTAL RETURNS
Russell 2000 Small-Cap Index Fund
As of 12/31
 
During the ten-year period shown in the bar chart, the highest return for a quarter was 31.35% (quarter ended December 31, 2020) and the lowest return for a quarter was -30.51% (quarter ended March 31, 2020).  
For the periods ended 12/31/25
Average Annual Total Returns
1 Year
5 Years
10 Years
iShares Russell 2000 Small-Cap Index Fund - Class K Shares
Return Before Taxes
12.83
%
6.11
%
9.66
%
Return After Taxes on Distributions
11.80
%
4.95
%
8.55
%
Return After Taxes on Distributions and Sale of Fund Shares
7.98
%
4.50
%
7.57
%
Russell 3000® Index
(Reflects no deduction for fees, expenses or taxes)
17.15
%
13.15
%
14.29
%
Russell 2000® Index
(Reflects no deduction for fees, expenses or taxes)
12.81
%
6.09
%
9.62
%
 
After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Investment Manager
The Series' investment manager is BlackRock Advisors, LLC (previously defined as "BlackRock"). The Series' sub-adviser is BlackRock Fund Advisors (the "Sub-Adviser"). Where applicable, the use of the term "BlackRock" also refers to the Series' Sub-Adviser.
Portfolio Managers  
Portfolio Manager
Portfolio Manager
of the Series Since
Title
Jennifer Hsui, CFA
2016
Managing Director of BlackRock, Inc.
Matt Waldron, CFA
2025
Managing Director of BlackRock, Inc.
Peter Sietsema, CFA
2025
Managing Director of BlackRock, Inc.
Steven White
2025
Managing Director of BlackRock, Inc.
 
Purchase and Sale of Fund Shares
Class K Shares of the Fund are available only to (i) certain employee benefit plans, such as health savings accounts, and certain employer-sponsored retirement plans (not including SEP IRAs, SIMPLE IRAs and SARSEPs) (collectively, "Employer-Sponsored Retirement Plans"), (ii) collective trust funds, investment companies and other pooled investment vehicles, each of which may purchase shares of the Fund through a Financial Intermediary that has entered
5
into an agreement with the Fund's distributor to purchase such shares, (iii) "Institutional Investors," which include, but are not limited to, endowments, foundations, family offices, banks and bank trusts, local, city, and state governmental institutions, corporations and insurance company separate accounts, each of which may purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund's distributor to purchase such shares, (iv) clients of private banks that purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund's distributor to sell such shares, (v) fee-based advisory platforms of a Financial Intermediary that (a) has specifically acknowledged in a written agreement with the Distributor and/or its affiliate(s) that the Financial Intermediary shall offer such shares to fee-based advisory clients through an omnibus account held at the Fund or (b) transacts in the Fund's shares through another intermediary that has executed such an agreement and (vi) any other investors who met the eligibility criteria for BlackRock Shares or Class K Shares prior to August 15, 2016 and have continually held Class K Shares of the Fund in the same account since August 15, 2016.
You may purchase or redeem shares of the Fund each day the New York Stock Exchange is open. Purchase orders may also be placed by calling (800) 537-4942, by mail (c/o BlackRock, P.O. Box 534429, Pittsburgh, Pennsylvania 15253-4429), or online at www.blackrock.com. Institutional Investors are subject to a $5 million minimum initial investment requirement. Other investors, including Employer-Sponsored Retirement Plans, have no minimum initial investment requirement. There is no minimum investment amount for additional purchases.
Tax Information
Different income tax rules apply depending on whether you are invested through a qualified tax-exempt plan described in section 401(a) of the Internal Revenue Code of 1986, as amended. If you are invested through such a plan (and Fund shares are not "debt-financed property" to the plan), then the dividends paid by the Fund and the gain realized from a redemption or exchange of Fund shares will generally not be subject to U.S. federal income taxes until you withdraw or receive distributions from the plan. If you are not invested through such a plan, then the Fund's dividends and gain from a redemption or exchange may be subject to U.S. federal income taxes and may be taxed as ordinary income or capital gains, unless you are a tax-exempt investor.
Payments to Broker/Dealers and Other Financial Intermediaries
If you purchase shares of the Fund through a Financial Intermediary, the Fund and BlackRock Investments, LLC, the Fund's distributor or its affiliates may pay the Financial Intermediary for the sale of Fund shares and related services.
These payments may create a conflict of interest by influencing the Financial Intermediary and your individual financial professional to recommend the Fund over another investment.
Class K Shares are only available through a Financial Intermediary if the Financial Intermediary will not receive from Fund assets, or the Fund's distributor's or an affiliate's resources, any commission payments, shareholder servicing fees (including sub-transfer agent and networking fees), or distribution fees (including Rule 12b-1 fees) with respect to assets invested in Class K Shares.
Ask your individual financial professional or visit your Financial Intermediary's website for more information.
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INVESTMENT COMPANY ACT FILE # 811-07899
SPRO-RUS2-K-0426
 
 
Blackrock Index Funds Inc. published this content on May 05, 2026, and is solely responsible for the information contained herein. Distributed via EDGAR on May 05, 2026 at 17:52 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]