X0609 4 2026-04-27 0001478320 Adaptive Biotechnologies Corp ADPT 0001780664 RUBINSTEIN JULIE false C/O ADAPTIVE BIOTECHNOLOGIES CORPORATION 1165 EASTLAKE AVENUE EAST SEATTLE WA 98109 0 1 0 0 President and COO 1 Common Stock 2026-04-27 4 M 0 14707 8.46 A 396839 D Common Stock 2026-04-27 4 S 0 19037 14.23 D 377802 D Stock Option (right to buy) 8.46 2026-04-27 4 M 0 14707 0 D 2033-03-06 Common Stock 14707 45731 D The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 18, 2025. The price reported for this transaction is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.08 to $14.34, 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 options vested with respect to 1/4 of such shares on March 4, 2024, with 1/48 of such shares vesting thereafter at the end of each full month of continuous service until fully vested. /s/ Julie Rubinstein by Kyle Piskel, Attorney-in-Fact 2026-04-29