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: 811-07332 and 811-08162

Name of Fund: BlackRock Funds III

BlackRock Cash Funds: Institutional

BlackRock Cash Funds: Treasury

BlackRock LifePath^® Dynamic Retirement Fund

BlackRock LifePath^® Dynamic 2025 Fund

BlackRock LifePath^® Dynamic 2030 Fund

BlackRock LifePath^® Dynamic 2035 Fund

BlackRock LifePath^® Dynamic 2040 Fund

BlackRock LifePath^® Dynamic 2045 Fund

BlackRock LifePath^® Dynamic 2050 Fund

BlackRock LifePath^® Dynamic 2055 Fund

BlackRock LifePath^® Dynamic 2060 Fund

BlackRock LifePath^® Dynamic 2065 Fund

BlackRock LifePath^® Index Retirement Fund

BlackRock LifePath^® Index 2025 Fund

BlackRock LifePath^® Index 2030 Fund

BlackRock LifePath^® Index 2035 Fund

BlackRock LifePath^® Index 2040 Fund

BlackRock LifePath^® Index 2045 Fund

BlackRock LifePath^® Index 2050 Fund

BlackRock LifePath^® Index 2055 Fund

BlackRock LifePath^® Index 2060 Fund

BlackRock LifePath^® Index 2065 Fund

iShares MSCI Total International Index Fund

iShares Russell 1000 Large-Cap Index Fund

iShares S&P 500 Index Fund

iShares U.S. Aggregate Bond Index Fund

                         Master Investment Portfolio

Diversified Equity Master Portfolio (Formerly Active Stock Master Portfolio)

International Tilts Master Portfolio

Large Cap Index Master Portfolio

Money Market Master Portfolio

S&P 500 Index Master Portfolio

Total International ex U.S. Index Master Portfolio

Treasury Money Market Master Portfolio

U.S. Total Bond Index Master Portfolio

Fund Address:    100 Bellevue Parkway, Wilmington, DE 19809

Name and address of agent for service: John M. Perlowski, Chief Executive Officer, BlackRock Funds III and

             Master Investment Portfolio, 55 East 52^nd Street, New York, NY 10055

Registrants’ telephone number, including area code: (800) 537-4942

Date of fiscal year end: 12/31/2020

Date of reporting period: 06/30/2020

Item 1 – Report to Stockholders

2

		JUNE 30, 2020

BlackRock Funds III

Table of Contents

Money Market Overview  For the Six-Month Period Ended June 30, 2020

At the onset of 2020, the economy was in a good place and interest rate policy was appropriate according to the Fed, but this outlook quickly changed upon the imposition of dramatic measures by authorities around the world to stem the spread of the coronavirus pandemic. In response, the Fed quickly enacted a series of unprecedented measures to channel credit to businesses and households and smooth market functioning.

The Fed’s stimulus campaign began with an “emergency” 0.50% cut to the Federal Funds target rate on March 3, 2020. This action was followed up a few weeks later with a surprise 1% interest rate cut, bringing the range for the Federal Funds target rate to 0.00%-0.25%. This action included a commitment to keep rates low until the uncertainty has passed. Dusting off its crisis-era playbook, the Fed rebooted or rolled out various support facilities and continues to emphasize its support of credit and liquidity in order to stabilize markets.

The most impactful measure for money market funds, in our view, was the creation of the Money Market Liquidity Facility to purchases commercial paper and domestic and Yankee certificates of deposit from prime money market funds, and municipal debt and variable rate demand notes from municipal money market funds.

The facility was largely active and provided liquidity to money market funds by the end of the first quarter of 2020. In a nod to 2008, the Fed revived the following vehicles: the Commercial Paper Funding Facility to backstop the purchase of high-quality commercial paper from U.S. issuers; the Primary Dealer Credit Facility to provide low-cost funding against a broad range of collateral including commercial paper; and the Term Asset-Backed Securities Loan Facility to purchase asset-backed securities.

Other notable actions included the creation of new facilities to purchase investment-grade corporate debt through the Primary Market Corporate Credit Facility and Secondary Market Corporate Credit Facility. A $2 trillion fiscal aid package signed into law by President Trump along with a series of coordinated global fiscal and monetary actions complemented the Fed’s sweeping measures.

While no new policy initiatives were announced at the June 10, 2020 Federal Open Market Committee meeting, Chairman Powell acknowledged during the post-meeting press conference that two additional policy tools, so-called forward guidance and the targeting of interest rates along the yield curve, were both discussed. Minutes of the meeting released on July 1 revealed that “participants generally indicated support for outcome-based forward guidance.”

According to the Investment Company Institute (“ICI”), prime money market fund assets across the industry recouped over two-thirds of the outflows experienced during the first quarter of 2020, standing around $761 billion at the quarter’s end.

By contrast, over the second quarter, government money market fund assets industrywide declined more than $160 billion since peaking at over $3.9 trillion on May 13, 2020 per the ICI. According to Wrightson ICAP (a research firm that specializes in analysis of federal reserve operations and policy, economic data, and Treasury financing trends), net new Treasury bill supply was robust in the second quarter of 2020, totaling $2.4 trillion. Rates across the Treasury bill curve were up modestly as of June 30 relative to the end of the first quarter of 2020, as markets digested heavy Treasury bill supply.

The three-month London Interbank Offered Rate overnight indexed swap spread — a gauge of stress in the financial system — declined to 0.24% as of June 30, 2020 from 1.38% as on March 31, 2020. A sign, in our view, of normalizing over the quarter.

Usage of the Money Market Mutual Fund Liquidity Facility — which is intended to serve as a backstop source of liquidity for prime and municipal money market funds — steadily declined throughout the second quarter. As of July 1, 2020, usage stood at around $20.6 billion, which is down over $32 billion from the peak level seen on April 8, 2020.

In our view, some of the excess liquidity that was amassed in money market funds in March and April is slowly being deployed elsewhere, and we expect to see additional outflows from money market funds in advance of the July 15 federal income tax filing date.

Net new Treasury bill issuance, in our assessment, could be tempered in the near term given the ample cash balance of over $1.6 trillion in the Treasury General Account at the Fed as of July 1, 2020. Looking ahead, we believe a heavier-than-expected pace of disbursements from the Treasury General Account or passage of additional fiscal stimulus at the federal level could result in a resumption of more robust Treasury bill supply.

We expect credit spreads to remain range bound over the course of the third quarter of 2020. Going forward, we will be monitoring how successful economies are at restarting activity while controlling the coronavirus spread as well as the effectiveness of policy implementation.

Past performance is no guarantee of future results. Index performance is shown for illustrative purposes only. You cannot invest directly in an index.

BlackRock Cash Funds: Institutional

BlackRock Cash Funds: Institutional’s (the “Fund”) investment objective is to seek a high level of income consistent with liquidity and the preservation of capital.

BlackRock Cash Funds: Treasury

BlackRock Cash Funds: Treasury’s (the “Fund”) investment objective is to seek current income consistent with liquidity and stability of principal.

The 7-Day SEC Yields may differ from the 7-Day Yields shown due to the fact that the 7-Day SEC Yields exclude distributed capital gains.

Past performance is not indicative of future results.

Disclosure of Expenses

Shareholders of the Funds may incur the following charges: (a) transactional expenses; and (b) operating expenses, including administration fees, service and distribution fees, and other fund expenses. The expense examples shown below (which are based on a hypothetical investment of $1,000 invested on January 1, 2020 and held through June 30, 2020) are intended to assist shareholders both in calculating expenses based on an investment in each Fund and in comparing these expenses with similar costs of investing in other mutual funds.

The expense examples provide information about actual account values and actual expenses. In order to estimate the expenses a shareholder paid during the period covered by this report, shareholders can divide their account value by $1,000 and then multiply the result by the number corresponding to their share class under the heading entitled “Expenses Paid During the Period.”

The expense examples also provide information about hypothetical account values and hypothetical expenses based on a Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses. In order to assist shareholders in comparing the ongoing expenses of investing in these Funds and other funds, compare the 5% hypothetical examples with the 5% hypothetical examples that appear in shareholder reports of other funds.

The expenses shown in the expense examples are intended to highlight shareholders’ ongoing costs only and do not reflect transactional expenses, such as sales charges, if any. Therefore, the hypothetical examples are useful in comparing ongoing expenses only, and will not help shareholders determine the relative total expenses of owning different funds. If these transactional expenses were included, shareholder expenses would have been higher.

Expense Examples

Statements of Assets and Liabilities  (unaudited)

June 30, 2020

See notes to financial statements.

Statements of Operations  (unaudited)

Six Months Ended June 30, 2020

See notes to financial statements.

Statements of Changes in Net Assets

See notes to financial statements.

Financial Highlights

(For a share outstanding throughout each period)

See notes to financial statements.

Financial Highlights  (continued)

(For a share outstanding throughout each period)

See notes to financial statements.

Financial Highlights  (continued)

(For a share outstanding throughout each period)

See notes to financial statements.

Notes to Financial Statements  (unaudited)

BlackRock Funds III (the “Trust”) is registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as an open-end management investment company. The Trust is organized as a Delaware statutory trust. The following, each of which is a series of the Trust, are referred to herein collectively as the “Funds” or individually as a “Fund”:

Each Fund seeks to achieve its investment objective by investing all of its assets in a corresponding series of Master Investment Portfolio (“MIP”): Money Market Master Portfolio and Treasury Money Market Master Portfolio (each, a “Master Portfolio” and together, the “Master Portfolios”). MIP is an affiliate of the Trust. Each Master Portfolio has the same investment objective and strategies as its corresponding Fund. The value of each Fund’s investment in its corresponding Master Portfolio reflects the Fund’s proportionate interest in the net assets of the Master Portfolio. The performance of each Fund is directly affected by the performance of the Master Portfolios. At June 30, 2020, the percentage of each Master Portfolio owned by its corresponding Fund was 100% for Institutional and 93% for Treasury. The financial statements of the Master Portfolios, including the Schedules of Investments, are included elsewhere in this report and should be read in conjunction with the Funds’ financial statements.

Institutional only offers SL Agency share class and is only available for certain eligible investors. Treasury offers multiple classes of shares. Institutional, Select, SL Agency, Capital, Premium and Trust Shares are sold without a sales charge and only to certain eligible investors. All classes of shares have identical voting, dividend, liquidation and other rights and are subject to the same terms and conditions, and differ principally with respect to administration fees.

The Board of Trustees of the Trust and Board of Directors of MIP are referred to throughout this report as the “Board” and the members are referred to as “Trustees.”

Treasury operates as a “government money market fund” under Rule 2a-7 under the 1940 Act. The Fund is not subject to liquidity fees or temporary suspensions of redemptions due to declines in the Fund’s weekly liquid assets.

Institutional began pricing and transacting its shares at a net asset value (“NAV”) per share calculated to four decimal places, reflecting market-based values of its portfolio holdings (i.e., at a “floating” NAV).

With respect to Institutional, the Board is permitted to impose a liquidity fee of up to 2% on the value of shares redeemed or temporarily restrict redemptions from Institutional for up to 10 business days during a 90 day period, in the event that Institutional’s weekly liquid assets fall below certain thresholds.

The Funds, together with certain other registered investment companies advised by BlackRock Advisors, LLC (the “Manager”) or its affiliates, are included in a complex of equity, multi-asset, index and money market funds referred to as the BlackRock Multi-Asset Complex.

The financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”), which may require management to make estimates and assumptions that affect the reported amounts of assets and liabilities in the financial statements, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. Each Fund is considered an investment company under U.S. GAAP and follows the accounting and reporting guidance applicable to investment companies. Below is a summary of significant accounting policies:

Investment Transactions and Income Recognition: For financial reporting purposes, contributions to and withdrawals from the Master Portfolios are accounted for on a trade date basis. The Funds record their proportionate share of the Master Portfolio’s income, expenses and realized and unrealized gains and losses on a daily basis. In addition, the Funds accrue their own expenses. Income, expenses and realized and unrealized gains and losses are allocated daily to each class based on its relative net assets.

Distributions: Distributions from net investment income are declared daily and paid monthly. Distributions of capital gains are distributed at least annually and are recorded on the ex-dividend dates. The character and timing of distributions are determined in accordance with U.S. federal income tax regulations, which may differ from U.S. GAAP.

Liquidity Fees: Any liquidity fees imposed on the value of shares redeemed in the event that Institutional’s weekly liquid assets fall below certain thresholds are recorded as paid-in-capital. The liquidity fees are collected and retained by Institutional for the benefit of Institutional’s remaining shareholders.

Indemnifications: In the normal course of business, a Fund enters into contracts that contain a variety of representations that provide general indemnification. A Fund’s maximum exposure under these arrangements is unknown because it involves future potential claims against a Fund, which cannot be predicted with any certainty.

Other: Expenses directly related to a Fund or its classes are charged to that Fund or the applicable class. Other operating expenses shared by several funds, including other funds managed by BlackRock Advisors, LLC (the “Administrator”), are prorated among those funds on the basis of relative net assets or other appropriate methods. Expenses directly related to the Funds and other shared expenses prorated to the Funds are allocated daily to each class based on their relative net assets or other appropriate methods.

Investment Valuation Policies: Each Fund’s policy is to value its financial instruments at fair value. Each Fund records its investment in the Master Portfolio at fair value based on the Funds’ proportionate interest in the net assets of the Master Portfolio. Valuation of securities held by the Master Portfolio is discussed in Note 3 of the Master Portfolios’ Notes to Financial Statements, which are included elsewhere in this report.

Notes to Financial Statements  (unaudited) (continued)

Administration: The Trust, on behalf of the Funds, entered into an Administration Agreement with BlackRock Advisors, LLC (“BAL”), which has agreed to provide general administrative services (other than investment advice and related portfolio activities). BAL has agreed to bear all of the Funds’ ordinary operating expenses, excluding, generally, investment advisory fees, distribution fees, brokerage and other expenses related to the execution of portfolio transactions, extraordinary expenses and certain other expenses which are borne by the Funds. BAL is entitled to receive for these administrative services an annual fee based on the average daily net assets of each Fund as follows:

From time to time, BAL may waive such fees in whole or in part. Any such waiver will reduce the expenses of the Funds and, accordingly, have a favorable impact on their performance. BAL may delegate certain of its administration duties to sub-administrators.

For the six months ended June 30, 2020, the following table shows the class specific administration fees borne directly by each share class of each Fund:

As of June 30, 2020, the only investors for the SL Agency Shares of Institutional are investment companies for which (i) BFA, BlackRock Institutional Trust Company, N.A. (“BTC”), or an affiliate provides investment advisory or administration services, or (ii) BTC acts as securities lending agent and which have directed BTC on their behalf to invest securities lending cash collateral in SL Agency Shares of Institutional. Affiliated shareholders in the SL Agency Shares of the Funds represent a significant portion of the outstanding shares and net assets of Institutional and Treasury.

Distribution Fees: The Trust, on behalf of the Funds, entered into a Distribution Agreement and a Distribution Plan with BlackRock Investments, LLC (“BRIL”), an affiliate of the Administrator. Shareholders of Capital, Institutional, Premium, Select, SL Agency and Trust Shares of the Funds do not pay any fees for distribution services.

Expense Waivers and Reimbursements: BAL contractually agreed to waive a portion of its administration fees for the Select Shares through April 30, 2021. After giving effect to such contractual expense waiver, the administration fees for the Select Shares will be 0.13%.

The fees and expenses of the Funds’ trustees who are not “interested persons” of the Trust, as defined in the 1940 Act (“Independent Trustees”), counsel to the Independent Trustees and the Trust’s independent registered public accounting firm (together, the “independent expenses”) are paid directly by the Funds. BAL has contractually agreed to reimburse the Funds or provide an offsetting credit against the administration fees paid by the Funds in an amount equal to these independent expenses through April 30, 2021. For the six months ended June 30, 2020, the amounts waived and/or reimbursed were as follows:

Interfund Lending: In accordance with an exemptive order (the “Order”) from the U.S. Securities and Exchange Commission (“SEC”), each Fund may participate in a joint lending and borrowing facility for temporary purposes (the “Interfund Lending Program”), subject to compliance with the terms and conditions of the Order, and to the extent permitted by each Fund’s investment policies and restrictions. Each Fund is currently permitted to borrow and lend under the Interfund Lending Program.

A lending BlackRock fund may lend in aggregate up to 15% of its net assets, but may not lend more than 5% of its net assets to any one borrowing fund through the Interfund Lending Program. A borrowing BlackRock fund may not borrow through the Interfund Lending Program or from any other source more than 33 1/3% of its total assets (or any lower threshold provided for by the fund’s investment restrictions). If a borrowing BlackRock fund’s total outstanding borrowings exceed 10% of its total assets, each of its outstanding interfund loans will be subject to collateralization of at least 102% of the outstanding principal value of the loan. All interfund loans are for temporary or emergency purposes and the interest rate to be charged will be the average of the highest current overnight repurchase agreement rate available to a lending fund and the bank loan rate, as calculated according to a formula established by the Board.

During the period ended June 30, 2020, the Funds did not participate in the Interfund Lending Program.

Trustees and Officers: Certain trustees and/or officers of the Trust are directors and/or officers of BlackRock, Inc. (“BlackRock”) or its affiliates.

Notes to Financial Statements  (unaudited) (continued)

It is each Fund’s policy to comply with the requirements of the Internal Revenue Code of 1986, as amended, applicable to regulated investment companies, and to distribute substantially all of its taxable income to its shareholders. Therefore, no U.S. federal income tax provision is required.

Each Fund files U.S. federal and various state and local tax returns. No income tax returns are currently under examination. The statute of limitations on each Fund’s U.S. federal tax returns generally remains open for each of the four years ended December 31, 2019. The statutes of limitations on each Fund’s state and local tax returns may remain open for an additional year depending upon the jurisdiction.

Management has analyzed tax laws and regulations and their application to the Funds as of June 30, 2020, inclusive of the open tax return years, and does not believe that there are any uncertain tax positions that require recognition of a tax liability in the Funds’ financial statements.

Transactions in capital shares for each class of Institutional were as follows:

The number of shares sold, reinvested and redeemed corresponds to the net proceeds from the sale of shares, reinvestment of all distributions and cost of shares redeemed, respectively, since shares are sold and redeemed at $1.00 per share for Treasury.

Transactions in capital shares for each class of Treasury were as follows:

Management has evaluated the impact of all subsequent events on the Funds through the date the financial statements were issued and has determined that there were no subsequent events requiring adjustment or additional disclosure in the financial statements.

Master Portfolio Information  as of June 30, 2020