Tax-driven share sale by Adaptive Biotechnologies (ADPT) Chief Scientific Officer

Rhea-AI Filing Summary

Adaptive Biotechnologies Corp Chief Scientific Officer Harlan S. Robins reported selling a total of 470,266 shares of common stock on March 11, 2026 at $13.17 per share. According to the footnotes, both sales were mandated "sell to cover" transactions to satisfy tax withholding on vesting RSUs and performance share units, and did not represent discretionary trading decisions. After these transactions, Robins directly owned 1,522,058 shares of Adaptive Biotechnologies common stock.

Insights

Insider trading and compensation analyst

Large CSO share sale is tax-driven, not discretionary.

The Chief Scientific Officer of Adaptive Biotechnologies, Harlan S. Robins, reported open-market sales totaling 470,266 common shares at $13.17 per share. On the surface, repeated code S transactions and a sizable net sale might look like significant insider selling.

However, the footnotes state these transactions were required to cover tax withholding from vesting RSUs and performance share units under the company’s equity plans. That means the sales were mechanistic, driven by tax obligations, rather than an active decision to reduce exposure based on the company’s prospects.

Robins still holds 1,522,058 common shares directly after the sales, indicating a substantial continuing stake. With no derivative positions listed and the sales framed as mandated sell-to-cover events, this filing reads as routine compensation-related activity rather than a change in strategic sentiment.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

ROBINS HARLAN S

(Last) (First) (Middle)

C/O ADAPTIVE BIOTECHNOLOGIES CORPORATION

1165 EASTLAKE AVENUE EAST

(Street)

SEATTLE WA 98109

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Adaptive Biotechnologies Corp [ ADPT ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Scientific Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/11/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/11/2026		S(1)		140,666	D	$13.17	1,851,658	D
Common Stock	03/11/2026		S(2)		329,600	D	$13.17	1,522,058	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 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.

2. 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	03/13/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Adaptive Biotechnologies (ADPT) report for Harlan S. Robins?

Adaptive Biotechnologies reported that Chief Scientific Officer Harlan S. Robins sold 470,266 common shares. The transactions occurred on March 11, 2026 at a price of $13.17 per share and were executed as open-market sales according to the Form 4 details.

Why did the Adaptive Biotechnologies (ADPT) CSO sell 470,266 shares?

The sales were made to cover tax withholding obligations on vesting equity awards. Footnotes explain the transactions were mandated "sell to cover" sales under the company’s equity incentive plans for RSU and performance share unit vesting, not discretionary trading by the executive.

How many Adaptive Biotechnologies (ADPT) shares does Harlan S. Robins hold after the sale?

After the reported transactions, Harlan S. Robins directly owns 1,522,058 common shares. This post-transaction holding reflects his remaining equity stake following the tax-driven sale of 470,266 shares disclosed in the Form 4 filing.

Were the Adaptive Biotechnologies (ADPT) insider sales discretionary trades?

No, the filing states the sales did not represent discretionary trades. The company’s footnotes specify the transactions were required to fund tax withholding via "sell to cover" mechanisms linked to vesting RSUs and performance share units under equity incentive plans.

What type of securities were involved in the Adaptive Biotechnologies (ADPT) CSO transactions?

The transactions involved Adaptive Biotechnologies common stock. Two non-derivative transactions coded as open-market sales (code S) were reported, both at a price of $13.17 per share, tied to tax obligations from vesting equity awards rather than option exercises or derivative conversions.

Does the Form 4 for Adaptive Biotechnologies (ADPT) show any remaining derivative positions for the CSO?

No derivative positions are listed for Harlan S. Robins in this Form 4. The derivativeSummary section is empty, and the reported activity relates only to non-derivative common stock sold to satisfy tax obligations from vesting stock-based compensation.