Company: MYI
Filing Date: 2025-09-05
Form Type: 424B3
Source: 0001193125-25-196285
Chunk: 346

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-09-05
Form: 424B3
Chunk 346
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 | Underwrite securities of other issuers except insofar as the Fund may be deemed an underwriter under the 
 Securities Act of 1933, as amended, in selling portfolio securities.                                     |

| • |     | Make loans to other persons, except that the Fund may purchase MIY Municipal Bonds and other debt securities 
 in accordance with its investment objective, policies and limitation.                                        |

| • |     | Purchase any securities on margin, except that the Fund may obtain such short-term credit as may be necessary                                                                                                                                          
 for the clearance of purchases and sales of portfolio securities (the deposit or payment by the Fund of initial or variation margin in connection with financial futures contracts and options thereon is not considered the purchase of a security on 
 margin).                                                                                                                                                                                                                                               |

| • |     | Make short sales of securities or maintain a short position or invest in put, call, straddle or spread                                                                                                               
 options, except that the Fund may write, purchase and sell options and futures on MIY Municipal Bonds, U.S. Government obligations and related indices or otherwise in connection with bona fide hedging activities. |

| • |     | Invest more than 25% of its total assets (taken at market value at the time of each investment) in securities                                                                           
 of issuers in a single industry; provided that, for purposes of this restriction, states municipalities and their political subdivisions are not considered to be part of any industry. |

For purposes of fundamental investment restriction (4) above, the Fund may borrow money in excess of 5% of the value of its total assets to the extent permitted by Section 18 of the 1940 Act or otherwise as permitted by applicable law for the purpose of repurchasing shares of common stock or redeeming shares of preferred stock. For purposes of fundamental investment restriction (9) above, the exception for states, municipalities and their political subdivisions applies only to tax-exemptsecurities issued by such entities. An additional investment restriction adopted by the Fund, which may be changed by the Board without shareholder approval, provides that the Fund may not mortgage, pledge, hypothecate or in any manner transfer, as security for indebtedness, any securities owned or held by the Fund except as may be necessary in connection with borrowings mentioned in investment restriction (4) above or except as may be necessary in connection with transactions in financial futures contracts and options thereon. If a percentage restriction on the investment policies or the investment or use of assets set forth above is adhered to at the time a transaction is