X0306 4 2021-04-30 0 0001478320 Adaptive Biotechnologies Corp ADPT 0001799081 Taylor Stacy L C/O ADAPTIVE BIOTECHNOLOGIES 1551 EASTLAKE AVE E STE 200 SEATTLE WA 98102 0 1 0 0 SVP and General Counsel Common Stock 2021-04-30 4 M 0 1042 7.80 A 16078 D Common Stock 2021-04-30 4 M 0 1770 6.55 A 17848 D Common Stock 2021-04-30 4 M 0 1354 31.71 A 19202 D Common Stock 2021-04-30 4 S 0 4166 41.93 D 15036 D Stock Option (Right to Buy) 7.80 2021-04-30 4 M 0 1042 0.00 D 2029-04-23 Common Stock 1042 25000 D Stock Option (Right to Buy) 6.55 2021-04-30 4 M 0 1770 0.00 D 2028-04-24 Common Stock 1770 19480 D Stock Option (Right to Buy) 31.71 2021-04-30 4 M 0 1354 0.00 D 2030-02-13 Common Stock 1354 46042 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 23, 2020. The price reported for this transaction is a weighted-average price. The shares were sold in multiple transactions ranging from $41.68 to 42.14, 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 April 23, 2020, with 1/48 of such shares vesting thereafter at the end of each full month of continuous service until fully vested. The options vested with respect to 1/4 of such shares on March 12, 2019, with 1/48 of such shares vesting thereafter at the end of each full month of continuous service until fully vested. The options vested with respect to 1/4 of such shares on February 13, 2021, with 1/48 of such shares vesting thereafter at the end of each full month of continuous service until fully vested. /s/ Stacy L. Taylor by Eric Billings as attorney-in-fact 2021-05-03