Company: MYI
Filing Date: 2025-09-05
Form Type: 424B3
Source: 0001193125-25-196285
Chunk: 41

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-09-05
Form: 424B3
Chunk 41
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, as applicable, and common shares as a single class. The quorum and voting requirements for each Fund are described in the section herein entitled “Voting Information and Requirements.”

This Joint Proxy Statement/Prospectus is only being delivered to the common shareholders of each Fund. Each Fund is separately
soliciting the votes of its respective preferred shareholders on each of the foregoing

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proposals that require the vote of preferred shareholders through a separate proxy statement and not through this Joint Proxy Statement/Prospectus. MVT, MIY, MVF and the Acquiring Fund are each formed as a Maryland corporation. Each of MVT, MIY, MVF and the Acquiring Fund is a diversified, closed-endmanagement investment company registered under the 1940 Act. The Reorganizations seek to achieve certain economies of scale and other operational efficiencies by combining four funds that have similar investment objectives and similar investment strategies, policies and restrictions. Assuming each of the Reorganizations receives the necessary approvals, 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 common shares and VRDP Shares of the Acquiring Fund in the form of book-entry interests. The Acquiring Fund will list the newly issued common shares on the New York Stock Exchange (“NYSE”). Such newly issued Acquiring Fund Shares will be distributed to MVT, MIY and MVF shareholders (although cash may be distributed in lieu of fractional common shares) and each of MVT, MIY and MVF will terminate its registration under the 1940 Act and liquidate, dissolve and terminate in accordance with its respective charter and Maryland law. The Acquiring Fund will continue to operate after the Reorganizations as a registered, diversified, closed-endmanagement investment company with the investment objective, investment strategies, investment policies and investment restrictions described in this Joint Proxy Statement/Prospectus. The Fund(s) in which you owned Shares on the Record Date is named on the proxy card. If you owned Shares in more than one Fund on the Record Date, you will receive more than one proxy card. Even if you plan to attend the Special Meeting, please sign, date and return EACH proxy card you receive or, if you provide voting instructions by telephone or via the Internet, please vote on each proposal affecting EACH Fund you own. If you vote by telephone or via the Internet, you will be asked to enter a unique code that has been assigned to you, which is printed on your proxy