[Form 4] Centessa Pharmaceuticals plc American Insider Trading Activity

Rhea-AI Filing Summary

Mario Alberto Accardi, an officer and director of Centessa Pharmaceuticals plc (CNTA), reported insider transactions on 09/09/2025. He exercised 5,000 share options at an $8.01 exercise price and received 5,000 ordinary shares. He also sold 7,000 ordinary shares at $20.00 under a Rule 10b5-1 trading plan adopted February 14, 2025. Following these transactions, Accardi beneficially owns 205,566 ordinary shares. The option exercised remains partially unvested per the disclosed vesting schedule (1/48th monthly with first installment March 1, 2024). The Form 4 is signed by an attorney-in-fact on Accardi's behalf.

Positive

• Detailed transaction disclosure: Form 4 lists exercise and sale with prices and post-transaction beneficial ownership
• Sale executed under Rule 10b5-1 plan: The filing states the sale was effected pursuant to a 10b5-1 trading plan adopted on February 14, 2025

Negative

• Net decrease in holdings: Beneficial ownership declined to 205,566 ordinary shares after the reported sale
• Partial vesting noted: Exercised options are subject to a vesting schedule (1/48th monthly), indicating not all option shares were immediately vested

Insights

Securities Analyst

TL;DR: Insider exercised options for 5,000 shares and sold 7,000 shares under a pre-established 10b5-1 plan; net holdings decreased to 205,566 shares.

The filing clearly documents an option exercise and an open-market sale executed the same day. The sale was made pursuant to a Rule 10b5-1 plan adopted on February 14, 2025, which indicates the sale was planned rather than opportunistic. The post-transaction beneficial ownership is 205,566 ordinary shares, and the exercised options have a stated vesting schedule (1/48th monthly, first vest March 1, 2024). From a disclosure standpoint the Form 4 provides the required transactional detail and proper attestation.

Corporate Governance Expert

TL;DR: Transactions are routine and documented; sale executed under a documented 10b5-1 plan, exercise follows standard option terms.

The filing contains standard governance disclosures: exercise price ($8.01), sale price ($20.00), transaction codes, and a vesting schedule for the option. The use of a substitute power of attorney for signature is noted. There are no indications in the filing of unusual timing, special related-party transfers, or amendments that would raise governance concerns based on the contents provided.

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^*

Accardi Mario Alberto

(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)
	President, Orexin Program

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		5,000	A	$8.01	212,566	D
Ordinary Shares(1)	09/09/2025		S(2)		7,000	D	$20	205,566	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			5,000	(3)	02/01/2034	Ordinary Shares(1)	5,000	$0	35,000	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 February 14, 2025.

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.

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 Mario Accardi report on Form 4?

He exercised 5,000 options at an $8.01 exercise price and sold 7,000 ordinary shares at $20.00 on 09/09/2025.

How many Centessa (CNTA) shares does Mario Accardi beneficially own after these transactions?

Following the reported transactions, Accardi beneficially owns 205,566 ordinary shares.

Was the sale by the insider discretionary or part of a plan?

The sale was executed pursuant to a Rule 10b5-1 trading plan adopted on February 14, 2025, as disclosed in the Form 4.

What are the exercise terms and vesting for the options exercised?

The exercised option had an $8.01 exercise price; vesting is 1/48th monthly with the first installment vesting March 1, 2024, per the filing.

Who signed the Form 4 for Mario Accardi?

The Form 4 was signed on Accardi's behalf by an attorney-in-fact, Raphael Deferiere, dated 09/11/2025.