X0609 4 2026-05-28 0 0000751978 VICOR CORP vicr 0000901484 VINCIARELLI PATRIZIO false C/O VICOR CORPORATION 25 FRONTAGE ROAD ANDOVER MA 01810 1 1 1 0 Chairman and CEO 1 Common Stock 167125 I See footnote Common Stock 2026-05-28 4 S 0 600 328.3733 D 8847490 D Common Stock 2026-05-28 4 S 0 400 330.25 D 8847090 D Common Stock 2026-05-28 4 S 0 900 333.4761 D 8846190 D Common Stock 2026-05-28 4 S 0 700 334.3086 D 8845490 D Common Stock 2026-05-28 4 S 0 420 335.7637 D 8845070 D Common Stock 2026-05-28 4 S 0 1303 336.6774 D 8843767 D Common Stock 2026-05-28 4 S 0 477 337.9609 D 8843290 D Common Stock 2026-05-28 4 S 0 1000 339.024 D 8842290 D Common Stock 2026-05-28 4 S 0 600 340.2517 D 8841690 D Common Stock 2026-05-28 4 S 0 1049 341.3245 D 8840641 D Common Stock 2026-05-28 4 S 0 2756 342.4912 D 8837885 D Common Stock 2026-05-28 4 S 0 1795 343.1585 D 8836090 D Common Stock 2026-05-28 4 S 0 1300 344.4492 D 8834790 D Common Stock 2026-05-28 4 S 0 530 345.531 D 8834260 D Common Stock 2026-05-28 4 S 0 1670 346.5091 D 8832590 D Common Stock 2026-05-28 4 S 0 1700 347.4478 D 8830890 D Common Stock 2026-05-28 4 S 0 2400 348.5783 D 8828490 D Common Stock 2026-05-28 4 S 0 200 349.175 D 8828290 D Common Stock 2026-05-28 4 S 0 200 350.42 D 8828090 D These shares are held by the reporting person as Trustee of the Patrizio Vinciarelli Irrevocable Trust U/A Dated 12/21/2012, established for the benefit of the child of the reporting person. This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 26, 2026. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $328.1000 to $328.7100. The reporting person undertakes to provide to Vicor Corporation, any security holder of Vicor Corporation, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (3) through (21) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $330.1800 to $330.3800. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $332.7800 to $333.7500. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $333.7900 to $334.6800. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $335.2600 to $336.2100. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $336.2800 to $337.2400. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $337.4000 to $338.3300. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $338.5700 to $339.5400. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $339.6200 to $340.6100. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $340.7000 to $341.6800. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $341.7300 to $342.7200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $342.7400 to $343.5200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $344.0200 to $344.8600. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $345.0200 to $346.0100. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $346.0300 to $346.8750. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $347.0400 to $347.9800. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $348.0700 to $349.0200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $349.1500 to $349.2000. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $350.4100 to $350.4300. /s/Quentin A. Fendelet Attorney in Fact for Patrizio Vinciarelli 2026-05-29