[Form 4] Adaptimmune Therapeutics plc American Insider Trading Activity

Rhea-AI Filing Summary

Adaptimmune Therapeutics plc reporting person William C. Bertrand, Jr., who is Chief Operating Officer and a director, disclosed the sale of 207,000 ordinary shares (represented by 34,500 ADSs) on 08/28/2025 at an ADS sale price of $0.0603 (equivalent to $0.01005 per ordinary share). After the reported sale he beneficially owns 986,352 ordinary shares (164,392 ADSs). The filing states he also holds RSU-style options and other options covering an aggregate of 16,108,722 ordinary shares. The Form 4 is signed 08/29/2025 and indicates the securities sold were ADSs representing ordinary shares.

Positive

• Timely, detailed disclosure of the insider sale including ADS-to-ordinary share conversion and price derivation
• Reporting person retains substantial option exposure (options covering 16,108,722 ordinary shares), indicating continued alignment with company performance

Negative

• Officer sold 34,500 ADSs (207,000 ordinary shares), a disclosed insider disposition that investors may view negatively
• Filing does not state whether the sale was executed pursuant to a Rule 10b5-1 trading plan or the reason for the sale

Insights

Securities Analyst

TL;DR: COO sold a small block of ADSs; he retains meaningful option exposure and substantial option-based holdings.

The reported sale of 34,500 ADSs (207,000 ordinary shares) by the COO is a clear disclosure event but not necessarily dispositive alone. The sale price of $0.0603 per ADS is explicit and the report shows the reporting person still holds 164,392 ADSs plus options covering 16,108,722 ordinary shares, indicating continued economic exposure to the issuer. For investors, the combination of disclosed cash sale and large option holdings suggests liquidity-taking rather than full divestiture; the filing does not state purpose of sale or any Rule 10b5-1 plan.

Corporate Governance Expert

TL;DR: Proper Section 16 disclosure filed; significant option holdings remain concentrated with the officer.

The Form 4 appears timely and includes required detail: transaction date, amount sold, price derivation, and post-transaction holdings. The filing documents that each ADS represents six ordinary shares and explains the per-share price calculation. The officer retains large option-based position (16.1 million ordinary-share equivalent), which is material from a governance and insider-concentration perspective. The filing does not declare any amendment or 10b5-1 plan checkbox, so no affirmative defense is disclosed.

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
Estimated average burden
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^*

Bertrand William C JR

(Last) (First) (Middle)

C/O ADAPTIMMUNE THERAPEUTICS PLC

60 JUBILEE AVENUE, MILTON PARK

(Street)

ABINGDON X0 OX14 4RX

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Adaptimmune Therapeutics PLC [ ADAP ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
08/28/2025

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
Ordinary Shares with a nominal value of GBP0.001 per share(1)	08/28/2025		S		207,000(2)	D	$0.0101(3)	986,352(4)	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. The ordinary shares whose sale is reported on this line are represented by American Depositary Shares ("ADS") and are held in the form of ADSs by the Reporting Person. Each ADS represents six ordinary shares of the Issuer.

2. The 207,000 ordinary shares reported in Column 4 are represented by 34,500 ADSs.

3. The price reported in Column 4 of $0.01005 per ordinary share is derived from the sale price of $0.0603 per ADS divided by six. These ADSs were sold in multiple transactions at a price of $0.0603. Upon request, the Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission with full information regarding the ADSs sold at this price in this footnote.

4. The 986,352 ordinary shares reported in Column 5 are held in the form of 164,392 ADSs by the Reporting Person and represent solely those ADSs held by the Reporting Person following this transaction. Additionally, the Reporting Person holds RSU-style options and other options covering an aggregate of 16,108,722 ordinary shares of the Issuer.

	/s/ William Charles Bertrand	08/29/2025
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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 did ADAP insider William C. Bertrand Jr. sell?

He sold 207,000 ordinary shares represented by 34,500 ADSs on 08/28/2025 at an ADS sale price of $0.0603 (equivalent to $0.01005 per ordinary share).

How many ADAP shares does William Bertrand own after the sale?

After the transaction he beneficially owns 986,352 ordinary shares held as 164,392 ADSs.

Does the filing show other holdings by the reporting person?

Yes. The filing discloses he holds RSU-style options and other options covering an aggregate of 16,108,722 ordinary shares.

When was the Form 4 signed and filed?

The signature on the filing is dated 08/29/2025 and the transaction date is 08/28/2025.

What price per ordinary share is reported and how is it derived?

The per-ordinary-share price is reported as $0.01005, derived from the ADS sale price of $0.0603 divided by six (each ADS represents six ordinary shares).