UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (date of earliest event reported): May 21, 2026

CENTESSA PHARMACEUTICALS PLC

(Exact name of Registrant, as specified in its charter)

Mailing address:

3rd Floor

1 Ashley Road

Altrincham

Cheshire WA14 2DT

United Kingdom

(Address of principal executive offices) (Zip code)

Registrant’s telephone number, including area code: +1 (617) 468-5770

Former name or address, if changed since last report:

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

At 11:59 p.m. on May 21, 2026, the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the “HSR Act”), expired with respect to the previously announced acquisition (the “Acquisition”) of the entire issued and to be issued share capital of Centessa Pharmaceuticals plc, a public limited company registered in England and Wales (the “Company” or “Centessa”) by Eli Lilly and Company (“Parent” or “Lilly”), by means of a court-sanctioned scheme of arrangement under Part 26 of the United Kingdom Companies Act of 2006 (the “Scheme of Arrangement”), pursuant to the Transaction Agreement, dated March 31, 2026 (the “Transaction Agreement”), by and among Centessa, Lilly and LDH XV Corporation.

The expiration of the waiting period under the HSR Act satisfies one of the conditions to the closing of the Acquisition. The closing of the Acquisition remains subject to other customary closing conditions set forth in the Transaction Agreement, including receipt of approval of Centessa’s shareholders and the sanction by the High Court of Justice of England and Wales of the Scheme of Arrangement and delivery of the court order to the Registrar of Companies in England and Wales.

UK Takeover Code Does Not Apply

Centessa Pharmaceuticals plc is not a company subject to regulation under the United Kingdom City Code on Takeovers and Mergers (the “UK Takeover Code”), therefore no dealing disclosures are required to be made under Rule 8 of the UK Takeover Code by shareholders of the Company or Parent.

Additional Information and Where to Find It

In connection with the proposed Acquisition, the Company filed a definitive proxy statement on Schedule 14A with the Securities and Exchange Commission (the “SEC”) on May 7, 2026 (the “Proxy Statement”), which was mailed to the Company’s shareholders. The Company may also file other documents with the SEC regarding the Acquisition. This Current Report is not a substitute for the Proxy Statement or any other document which the Company may file with the SEC. BEFORE MAKING ANY VOTING DECISION, SHAREHOLDERS ARE URGED TO READ THE PROXY STATEMENT (WHICH INCLUDES AN EXPLANATORY STATEMENT IN RESPECT OF THE SCHEME OF ARRANGEMENT OF THE COMPANY, IN ACCORDANCE WITH THE REQUIREMENTS OF THE U.K. COMPANIES ACT 2006) AND ANY OTHER RELEVANT DOCUMENTS THAT ARE FILED OR WILL BE FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO SUCH DOCUMENTS AND DOCUMENTS INCORPORATED BY REFERENCE THEREIN, CAREFULLY AND IN THEIR ENTIRETY (IF AND WHEN THEY BECOME AVAILABLE) BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. Any vote in respect of the resolutions to be proposed at the Company’s shareholder meeting to approve the Acquisition, the scheme or related matters, or other responses in relation to the Acquisition, should be made only on the basis of the information contained in the definitive proxy statement (including the scheme document). Shareholders may obtain a free copy of the Proxy Statement and other relevant documents containing important information about Parent, the Company and the Acquisition (if and when they become available) once such documents are filed with the SEC at the SEC’s website at www.sec.gov. Copies of the documents filed with the SEC by the Company will be available free of charge on the Company’s website at investors.centessa.com or by contacting the Company’s Investors Relations Department at investors@centessa.com.

Participants in the Solicitation

The Company, Parent and certain of their respective directors, executive officers and other employees may be deemed to be participants in the solicitation of proxies from the shareholders of the Company in respect of the Acquisition. The Company’s shareholders may obtain information regarding both the Company’s and Parent’s directors and executive officers, including a description of their direct or indirect interests, by security holdings or otherwise, in the Proxy Statement, any statements of beneficial ownership filed with the SEC after such proxy statement and any other relevant documents that are filed or will be filed with the SEC relating to the Acquisition. You may obtain free copies of these documents (if and when they become available) using the sources indicated above.

Cautionary Note Regarding Forward Looking Statements

This Current Report on Form 8-K contains “forward-looking statements” within the meaning of the federal securities laws, including Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended, including with respect to the Acquisition. Such forward-looking statements include, but are not limited to, statements regarding: the Acquisition; the parties’ ability to satisfy the conditions to the consummation of the Acquisition, including in connection with obtaining shareholder and High Court approvals, and the expected timetable for the Acquisition; and the anticipated occurrence, manner and timing of the closing of the Acquisition. All statements other than statements of historical facts are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements are based on current beliefs and expectations and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements.

These risks and uncertainties include, but are not limited to: the possibility that the Company’s shareholders may not approve the implementation of the Acquisition; the Scheme of Arrangement implementing the Acquisition is not sanctioned by the High Court of Justice of England and Wales; the Company’s receipt of any competing offers or acquisition proposals; a condition to closing of the Acquisition may not be satisfied (or waived); the ability of each party to consummate the Acquisition; the closing of the Acquisition might be delayed or not occur at all; the diversion of management time and attention from ongoing business operations and opportunities; the response of competitors to the Acquisition; the effect of the Acquisition on the Company’s operations and its relationships with its suppliers, business partners, management and employees, including its ability to attract and retain key personnel; the outcome of any legal proceedings that could be instituted against the parties to the Acquisition; the risks inherent in drug research, development and commercialization; disruption in the Company’s plans and operations attributable to the Acquisition; changes in the Company’s business during the period between announcement and closing of the Acquisition; the effects of the Acquisition on the Company’s share price; the risks related to non-achievement of any milestone and that holders of the CVRs will not receive any payments in respect of the CVRs; relationships with key third parties or governmental entities; regulatory changes and developments; and the impact of global macroeconomic conditions, including trade and other global disputes and interruptions, including related to tariffs, trade protection measures, and similar restrictions. For further discussion of these and other risks and uncertainties, see the “Risk Factors” section of the Company’s Quarterly Report on Form 10-Q filed with the SEC on May 5, 2026, as well as discussions of potential risks, uncertainties and other important factors, in the Company’s most recent filings with the SEC and in other filings that the Company makes with the SEC in the future. There can be no assurance that the Acquisition will be consummated in the anticipated timeframe or at all, that any event, change or other circumstance that could give rise to the termination of the definitive agreement for the Acquisition will not occur or that any product candidates will be approved on anticipated timelines or at all. All forward-looking statements in this Current Report are based on information available to the Company as of the date of this Current Report. The Company expressly disclaims any obligation to publicly update or revise the forward-looking statements, except as required by law.

No Offer or Solicitation

This Current Report on Form 8-K is for informational purposes only and is not intended to and does not constitute, or form part of, an offer, invitation or the solicitation of an offer or invitation to purchase, otherwise acquire, subscribe for, sell or otherwise dispose of any securities, or the solicitation of any vote or approval in any jurisdiction, pursuant to the Acquisition or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: May 22, 2026