Material Event (Form 8-K)

On December 30, 2025, Adaptive Biotechnologies Corporation (the "Company") announced that Digital Biotechnologies, Inc. ("Digital Biotechnologies"), a 70% owned subsidiary of the Company, held an initial closing of its Series A Preferred Stock financing, with total anticipated proceeds in the financing round of up to $15 million. Upon completion of the Series A round, the Company expects to retain a nearly 50% ownership interest in Digital Biotechnologies and to continue to consolidate the results of Digital Biotechnologies in the Company's financial statements.

This Form 8-Kcontains forward-looking statements that are based on management's beliefs and assumptions and on information currently available to management. All statements contained in this Form 8-Kother than statements of historical fact are forward-looking statements, including statements regarding completion of the Digital Biotechnologies' financing, total proceeds therefrom, and the Company's ownership interest in Digital Biotechnologies thereafter. In some cases, you can identify forward-looking statements by the words "anticipated," "expects," "continue," or other comparable terminology, although not all forward-looking statements contain these words. These statements involve risks, uncertainties and other factors that may cause actual results or achievements to be materially different from the information expressed or implied by these forward-looking statements. These risks, uncertainties and other factors are described under "Risk Factors," "Management's Discussion and Analysis of Financial Condition and Results of Operations" and elsewhere in the documents we file with the Securities and Exchange Commission from time to time, similar risks applicable to Digital Biotechnologies, and additional risks reflecting that Digital Biotechnologies is an early stage company with no revenues and limited activities to date. We caution you not to place undue reliance on forward-looking statements, which are inherently uncertain. The Company undertakes no obligation to update any forward-looking statements for any reason, except as required by law.