X0508 4 2026-02-20 0 0000106040 WESTERN DIGITAL CORP WDC 0002057088 Tregillis Cynthia L C/O WESTERN DIGITAL CORPORATION 5601 GREAT OAKS PARKWAY SAN JOSE CA 95119 0 1 0 0 Chief Legal Officer & Corp Sec 1 Common Stock 2026-02-20 4 M 0 3 0.0 A 136541 D Common Stock 2026-02-20 4 F 0 244 285.52 D 136297 D Common Stock 2026-02-21 4 M 0 9 0.0 A 136306 D Common Stock 2026-02-21 4 F 0 1109 285.52 D 135197 D Common Stock 2026-02-23 4 S 0 130 283.83 D 135067 D Common Stock 2026-02-24 4 S 0 308 281.7 D 134759 D Dividend Equivalent Rights 2026-02-20 4 M 0 3.234 0.0 D Common Stock 3.234 344.2281 D Dividend Equivalent Rights 2026-02-21 4 M 0 9.4399 0.0 D Common Stock 9.4399 334.7882 D The dividend equivalent rights were converted into, and paid in the form of, shares of the Issuer's common stock on a one-for-one basis in connection with the vesting of restricted stock units to which the dividend equivalent rights relate. A cash amount was also paid to the holder to settle a fractional dividend equivalent right. Payment of tax obligation by withholding securities incident to the vesting of securities in accordance with Rule 16b-3(e). The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 23, 2025. By: /s/ Sandra Garcia Attorney-in-Fact For: Cynthia Tregillis 2026-02-24