Company: MYI
Filing Date: 2025-09-05
Form Type: 424B3
Source: 0001193125-25-196285
Chunk: 242

Company: BLACKROCK MUNIYIELD QUALITY FUND III, INC.
Filing Date: 2025-09-05
Form: 424B3
Chunk 242
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.48%                      |     | 1.59%      |     | 2.49%      |     | 2.80%      |
| BlackRock MuniVest Fund, Inc.                   |     | MVF |     | 5.22%        |     | -0.08%     |     | 4.83%      |     | 1.13%                      |     | 1.77%      |     | 2.08%      |     | 1.47%      |
| BlackRock MuniYield Quality Fund III, Inc.      |     | MYI |     | 5.62%        |     | -0.19%     |     | 1.70%      |     | 1.35%                      |     | 1.85%      |     | 2.60%      |     | 2.55%      |

Because the Combined Fund will most closely resemble the Acquiring Fund, the Acquiring Fund will be the accounting survivor of the Reorganizations. The Combined Fund will also maintain the performance history of the Acquiring Fund at the closing of the Reorganizations. MVT’s charter authorizes the issuance of 199,990,823 shares of common stock, par value $0.10 per share (the “MVT Common Shares”) and 2,700 shares of Auction Market Preferred Stock, par value $0.05, with a liquidation preference of $25,000, plus an amount equal to all accumulated but unpaid dividends (whether or not earned or declared) (the “MVT AMPS Non-SeriesShares”), 900 shares of Auction Market Preferred Stock, Series A, par value $0.05, with a liquidation preference of $25,000, plus an amount equal to all accumulated but unpaid dividends (whether or not earned or declared) (the “MVT AMPS Series A Shares”), 900 shares of Auction Market Preferred Stock, Series B, par value $0.05, with a liquidation preference of $25,000, plus an amount equal to all accumulated but unpaid dividends (whether or not earned or declared) (the “MVT AMPS 135

Series B Shares”), 900 shares of Auction Market Preferred Stock, Series C, par value $0.05, with a liquidation preference of $25,000, plus an amount equal to all accumulated but unpaid
dividends (whether or not earned or declared)