X0508 4 2026-03-02 0 0001478320 Adaptive Biotechnologies Corp ADPT 0001780851 ROBINS HARLAN S C/O ADAPTIVE BIOTECHNOLOGIES CORPORATION 1165 EASTLAKE AVE E SEATTLE WA 98109 0 1 0 0 Chief Scientific Officer 1 Common Stock 2026-03-02 4 S 0 10000 15.72 D 1169524 D Common Stock 2026-03-03 4 S 0 14233 16.52 D 1155291 D The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 11, 2025. The price reported for this transaction is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.57 to $15.88, inclusive. The reporting person undertakes to provide to Adaptive Biotechnologies Corporation, any security holder of Adaptive Biotechnologies 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 any footnotes to this Form 4. The price reported for this transaction is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.50 to $16.55, inclusive. The reporting person undertakes to provide to Adaptive Biotechnologies Corporation, any security holder of Adaptive Biotechnologies 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 any footnotes to this Form 4. /s/ Harlan S. Robins by Kyle Piskel, Attorney-in-Fact 2026-03-04