Company: MYI
Filing Date: 2025-09-05
Form Type: 424B3
Source: 0001193125-25-196285
Chunk: 50

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-09-05
Form: 424B3
Chunk 50
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     |                       | -6.64 | % |
| Acquiring Fund (MYI) |     | $            | 10.38 |     | $   | 11.25 |     |                       | -7.73 | % |

21

To the extent MVT’s, MIY’s or MVF’s common shares are
trading at a wider discount (or a narrower premium) than the Acquiring Fund at the time of its Reorganization, MVT’s, MIY’s or MVF’s common shareholders would have the potential for an economic benefit by the narrowing of the
discount or widening of the premium. To the extent MVT’s, MIY’s or MVF’s common shares are trading at a narrower discount (or wider premium) than the Acquiring Fund at the time of its Reorganization, MVT’s, MIY’s or
MVF’s common shareholders may be negatively impacted if its Reorganization is consummated. Acquiring Fund common shareholders would only benefit from a premium/discount perspective to the extent the post-Reorganization discount (or premium) of
the Acquiring Fund common shares improves.

There can be no assurance that, after the Reorganizations, common shares of
the Combined Fund will trade at a narrower discount to NAV or wider premium to NAV than the common shares of any individual Fund prior to the Reorganizations. Upon consummation of the Reorganizations, the Combined Fund common shares may trade at a
price that is less than the current market price of Acquiring Fund common shares. In the Reorganizations, common shareholders of MVT, MIY and MVF will receive Acquiring Fund common shares based on the relative NAVs (not the market values) of the
respective Fund’s common shares. The market value of the common shares of the Combined Fund may be less than the market value of the common shares of each respective Fund prior to the Reorganizations.

If the Reorganization is approved by shareholders, effective upon the closing of the Reorganization, the Combined Fund will
adopt a discount management program under which the Combined Fund will, beginning in 2026, intend to offer to purchase a minimum of 5% of its outstanding common shares, subject to the Board’s discretion, at a price equal to 98% of NAV per
common share via annual tender offer if the Combined Fund’s common shares trade at an average daily discount to NAV of more than 10.00% during a measurement period beginning on January 1stand concluding on September 30