Company: MYI
Filing Date: 2025-06-11
Form Type: DEFA14A
Source: 0001193125-25-139223
Chunk: 0

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-06-11
Form: DEFA14A
Chunk 0
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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

| Check the appropriate box:            |     |                                                                |
| ☐   Preliminary Proxy Statement       |     | ☐   Confidential, for Use of the Commission Only (as permitted 
 by Rule 14a-6(e)(2))                                           |
| ☐   Definitive Proxy Statement        |     |                                                                |
| ☒   Definitive Additional Materials   |     |                                                                |
| ☐   Soliciting Material Pursuant to § 
 240.14a-12                            |     |                                                                |

BlackRock MuniHoldings California Quality Fund, Inc. BlackRock MuniHoldings Fund, Inc. BlackRock MuniHoldings New Jersey Quality Fund, Inc. BlackRock MuniHoldings Quality Fund II, Inc. BlackRock MuniYield Fund, Inc. BlackRock MuniYield Quality Fund II, Inc. BlackRock MuniYield Quality Fund III, Inc. BlackRock MuniYield Quality Fund, Inc. (Name of Registrant as Specified In Its Charter) (Name of Person(s) Filing Proxy Statement, if Other than the Registrant) Payment of Filing Fee (Check all boxes that apply):

| ☒   No fee required                                         |
| ☐   Fee paid previously with preliminary materials          |
| ☐   Fee computed on table in exhibit required by Item 25(b) 
 per Exchange Act Rules 14a-6(i)(1) and 0-11                 |

Your Vote Matters BlackRock Closed-EndFunds Why am I receiving this letter? You are receiving this reminder notice because you held shares in one or more of the BlackRock Closed- End Funds (the “Funds”) on May 19, 2025 and your Fund has not received your vote. Vote now to stop receiving solicitation notices and reduce costs for your Fund. What am I voting on? Proposal 1 is to elect to the Board of your Fund(s) the nominees named in the joint proxy statement.