Company: MYI
Filing Date: 2025-09-02
Form Type: N-14 8C/A
Source: 0001193125-25-193985
Chunk: 350

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-09-02
Form: N-14 8C/A
Chunk 350
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 Fitch and to comply with the Eligible Assets
requirement of the Articles Supplementary, the Fund will be required to comply with investment quality, diversification and other guidelines established by Moody’s and Fitch. Such guidelines will likely be more restrictive than the
restrictions set forth above.

MYI_PROXY_0825

B-6

The information in this statement of additional information is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This statement of additional information is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED SEPTEMBER 2, 2025

STATEMENT OF ADDITIONAL INFORMATION

BLACKROCK MUNIVEST FUND II, INC.

BLACKROCK MUNIYIELD MICHIGAN QUALITY FUND, INC.

BLACKROCK MUNIVEST FUND, INC.

BLACKROCK MUNIYIELD QUALITY FUND III, INC.

Dated [●]

This Statement of Additional Information is available to the common shareholders of BlackRock MuniVest Fund II, Inc. (NYSE Ticker: MVT)
(“MVT”), BlackRock MuniYield Fund, Inc. (NYSE Ticker: MIY) (“MIY”), BlackRock MuniVest Fund, Inc. (NYSE Ticker: MVF) (“MVF”), in connection with the Reorganization (each, a “Reorganization” and
collectively, the “Reorganizations”) of each of MVT, MIY and MVF into BlackRock MuniYield Quality Fund III, Inc. (NYSE Ticker: MYI) (“MYI” or the “Acquiring Fund,” and collectively with MVT, MIY and MVF, the
“Funds,” and each, a “Fund”), whereby the Acquiring Fund will acquire substantially all of the assets and assume substantially all of the liabilities of MVT, MIY and MVF in exchange solely for newly issued shares of the
Acquiring Fund’s common stock, par value $0.10 per share and Variable Rate Demand Preferred Shares, par value $0.10 per share and with a liquidation preference of $100,000 per share (“VRDP Shares” and the holders thereof,
“VRDP Holders”) (plus an amount equivalent to any accumulated and unpaid