X0609 4 2026-06-02 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 2026-06-02 4 S 0 500 316.9557 D 8787590 D Common Stock 2026-06-02 4 S 0 1200 318.473 D 8786390 D Common Stock 2026-06-02 4 S 0 1000 320.1789 D 8785390 D Common Stock 2026-06-02 4 S 0 1050 321.2444 D 8784340 D Common Stock 2026-06-02 4 S 0 1450 322.4707 D 8782890 D Common Stock 2026-06-02 4 S 0 808 323.4388 D 8782082 D Common Stock 2026-06-02 4 S 0 897 324.7237 D 8781185 D Common Stock 2026-06-02 4 S 0 1336 325.4353 D 8779849 D Common Stock 2026-06-02 4 S 0 1661 326.6634 D 8778188 D Common Stock 2026-06-02 4 S 0 600 327.8393 D 8777588 D Common Stock 2026-06-02 4 S 0 1171 328.9702 D 8776417 D Common Stock 2026-06-02 4 S 0 995 329.6283 D 8775422 D Common Stock 2026-06-02 4 S 0 1534 330.7832 D 8773888 D Common Stock 2026-06-02 4 S 0 3700 332.0834 D 8770188 D Common Stock 2026-06-02 4 S 0 1098 333.0437 D 8769090 D Common Stock 2026-06-02 4 S 0 1000 334.108 D 8768090 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 $316.6300 to $317.0200. 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 (18) 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 $318.1100 to $319.0900. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $319.5100 to $320.5000. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $320.8800 to $321.7400. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $321.9600 to $322.9200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $322.9600 to $323.9200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $323.9600 to $324.9200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $324.9600 to $325.9100. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $326.0900 to $327.0000. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $327.1800 to $328.1500. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $328.2200 to $329.2100. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $329.2200 to $330.1900. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $330.2900 to $331.2300. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $331.5000 to $332.4900. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $332.5200 to $333.4200. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $333.8700 to $334.5900. /s/Quentin A. Fendelet Attorney in Fact for Patrizio Vinciarelli 2026-06-03