[Form 4] Centessa Pharmaceuticals plc American Insider Trading Activity

Rhea-AI Filing Summary

Centessa Pharmaceuticals (CNTA) insider activity: Chief Technology & Quality Officer Tia L. Bush reported option exercises and matched sales on September 9-10, 2025. On 09/09/2025 she acquired 24,792 ordinary shares at $8.01 per share and on the same day sold 24,792 shares at $20 per share pursuant to a Rule 10b5-1 trading plan adopted September 14, 2024. On 09/10/2025 she acquired 25,000 shares at $9.42 and sold 25,000 shares at $22. Following the reported transactions, Ms. Bush beneficially owned 121,503 ordinary shares directly. The filing also discloses outstanding options: 24,792 shares underlying an option exercisable from 02/01/2034 (strike $8.01) and 25,000 shares underlying an option exercisable from 05/07/2031 (strike $9.42).

Positive

• The filing discloses that the reported sales were effected pursuant to a Rule 10b5-1 trading plan adopted on September 14, 2024, providing an affirmative defense disclosure.
• The report includes detailed derivative disclosures including option exercise prices, exercisable dates, and expiration dates for 24,792 and 25,000 share options.

Negative

• Direct beneficial ownership decreased to 121,503 ordinary shares following the reported transactions.
• The reporting officer sold 49,792 ordinary shares across the two days, reducing immediate insider shareholdings.

Insights

Securities Analyst

TL;DR: Officer exercised options and concurrently sold identical share amounts under a pre-established 10b5-1 plan, leaving 121,503 ordinary shares held.

The Form 4 reports option exercises on 09/09/2025 and 09/10/2025 that resulted in acquisitions of 24,792 and 25,000 ordinary shares at $8.01 and $9.42 respectively, followed by sales of the same share counts at $20 and $22 per share under a Rule 10b5-1 trading plan adopted on 09/14/2024. The filing quantifies remaining direct beneficial ownership at 121,503 shares and lists two outstanding option grants with stated vesting/expiration schedules. This is a routine Section 16 disclosure documenting insider liquidity executed under an affirmative defense trading plan.

Corporate Governance Expert

TL;DR: Transactions were executed under a disclosed 10b5-1 plan and accompanied by a substitute power of attorney signature.

The report includes an explicit statement that the reported sales were effected pursuant to a Rule 10b5-1 trading plan adopted on September 14, 2024, and attaches Exhibit 24.2 (Substitute Power of Attorney). The Form 4 is signed by an attorney-in-fact, consistent with delegated filing authority. All material items required on Form 4 are reported: transaction codes, amounts, prices, option terms, and post-transaction holdings.

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).

X

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^*

Bush Tia L

(Last) (First) (Middle)

C/O CENTESSA PHARMACEUTICALS PLC

3RD FL., 1 ASHLEY RD, ALTRINCHAM

(Street)

CHESHIRE X0 WA14 2DT

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Centessa Pharmaceuticals plc [ CNTA ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Technology & Quality Ofc

3. Date of Earliest Transaction (Month/Day/Year)
09/09/2025

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(1)	09/09/2025		M		24,792	A	$8.01	146,295	D
Ordinary Shares(1)	09/09/2025		S(2)		24,792	D	$20	121,503	D
Ordinary Shares(1)	09/10/2025		M		25,000	A	$9.42	146,503	D
Ordinary Shares(1)	09/10/2025		S(2)		25,000	D	$22	121,503	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
Share Option (right to buy)	$8.01	09/09/2025		M			24,792	(3)	02/01/2034	Ordinary Shares(1)	24,792	$0	145,208	D
Share Option (right to buy)	$9.42	09/10/2025		M			25,000	(4)	05/07/2031	Ordinary Shares(1)	25,000	$0	475,338	D

Explanation of Responses:

1. The Ordinary Shares may be represented by American Depositary Shares, each of which currently represents one Ordinary Share.

2. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 14, 2024.

3. 1/48th of the shares subject to such option shall vest and become exercisable in equal monthly installments with the first installment vesting on March 1, 2024.

4. 25% of the shares subject to such option shall vest and become exercisable on May 20, 2022 and the remaining 75% of the shares subject to such option shall vest and become exercisable in 36 monthly installments on the first day of each month thereafter.

Remarks:

Exhibit 24.2 - Substitute Power of Attorney

	/s/ Raphael Deferiere, attorney-in-fact	09/11/2025
	** 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 transactions did CNTA insider Tia L. Bush report on Form 4?

The Form 4 reports that on 09/09/2025 Ms. Bush acquired 24,792 ordinary shares at $8.01 and sold 24,792 shares at $20; on 09/10/2025 she acquired 25,000 shares at $9.42 and sold 25,000 shares at $22.

Were the sales made under a pre-arranged trading plan for CNTA?

Yes. The Form 4 states the sales were effected pursuant to a Rule 10b5-1 trading plan adopted on September 14, 2024.

How many CNTA shares does Tia L. Bush beneficially own after these transactions?

Following the reported transactions, Ms. Bush beneficially owned 121,503 ordinary shares directly.

What derivative securities does the Form 4 disclose for the reporting person?

The filing discloses two option grants: one for 24,792 shares (strike $8.01, exercisable beginning 02/01/2034, expiring 02/01/2034 per table) and one for 25,000 shares (strike $9.42, exercisable 05/07/2031, expiring 05/07/2031 per table).

Who signed the Form 4 filing for the reporting person?

The filing is signed by /s/ Raphael Deferiere, attorney-in-fact dated 09/11/2025, and references Exhibit 24.2 (Substitute Power of Attorney).