X0508 4 2026-03-11 0001478320 Adaptive Biotechnologies Corp ADPT 0001780851 ROBINS HARLAN S C/O ADAPTIVE BIOTECHNOLOGIES CORPORATION 1165 EASTLAKE AVENUE EAST SEATTLE WA 98109 0 1 0 0 Chief Scientific Officer 0 Common Stock 2026-03-11 4 S 0 140666 13.17 D 1851658 D Common Stock 2026-03-11 4 S 0 329600 13.17 D 1522058 D This transaction represents the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of RSUs. This sale is mandated by Issuer's election under the equity incentive plans to require the satisfaction of tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the Reporting Person. This transaction represents the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of performance share units. This sale is mandated by the Issuer's election under its equity incentive plans to require the satisfaction of tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the Reporting Person. /s/ Harlan S Robins by Kyle Piskel, Attorney-in-Fact 2026-03-13