Company: ADPT
Filing Date: 2025-04-29
Form Type: DEF 14A
Source: 0001193125-25-103752
Chunk: 0

Company: Adaptive Biotechnologies Corp
Filing Date: 2025-04-29
Form: DEF 14A
Chunk 0
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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box:

| ☐ | Preliminary Proxy Statement |

| ☐ | Confidential, for Use of the Commission Only (as permitted by Rule14a-6(e)(2)) |

| ☒ | Definitive Proxy Statement |

| ☐ | Definitive Additional Materials |

| ☐ | Soliciting Material under§240.14a-12 |

Adaptive Biotechnologies Corporation (Name of Registrant as Specified In Its Charter) (Name of Person(s) Filing Proxy Statement, if Other Than the Registrant) Payment of Filing Fee (Check the appropriate box):

| ☒ | No fee required |

| ☐ | Fee paid previously with preliminary materials |

| ☐ | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules14a-6(i)(1)and0-11. |

April 29, 2025

Dear Adaptive Biotechnologies Corporation Shareholder:

You are cordially invited to the Adaptive Biotechnologies Corporation 2025 Annual Meeting of Shareholders (the “Annual Meeting”). The attached proxy is solicited on behalf of the board of directors of Adaptive Biotechnologies Corporation for use at the Annual Meeting to be held on Tuesday, June 10, 2025, at 9:00 a.m., Pacific Time, or at any adjournment or postponement thereof, for the purposes set forth in the accompanying proxy statement, Notice of Annual Meeting of Shareholders (the “Notice”) and form of proxy. The Annual Meeting will be held entirely via the Internet, broadcast from our corporate headquarters at 1165 Eastlake Avenue East, Seattle, Washington 98109.

To be admitted to the Annual Meeting, you must register prior to Friday, June 6, 2025, at 5:00 p.m., Pacific Time at www.proxydocs.com/ADPT and enter the control number found on your proxy card, voting instruction form or Notice of Internet Availability of Proxy Materials you previously received. You may attend the meeting, vote your shares and submit questions electronically during the meeting via live webcast by registering at www.proxydocs.com/ADPT. You must also follow subsequent instructions you may receive by electronic mail