NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, DIRECTLY OR INDIRECTLY, IN WHOLE OR IN PART IN, INTO OR FROM ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH JURISDICTION.

THIS IS NOT AN ANNOUNCEMENT OF A FIRM INTENTION TO MAKE AN OFFER UNDER RULE 2.7 OF THE CITY CODE ON TAKEOVERS AND MERGERS (THE "CODE") AND THERE CAN BE NO CERTAINTY THAT AN OFFER WILL BE MADE, NOR AS TO THE TERMS ON WHICH ANY OFFER MIGHT BE MADE.

FOR IMMEDIATE RELEASE

12 December 2024

Statement regarding a possible all-share offer for

Tullow Oil plc by Kosmos Energy Ltd.

Kosmos Energy Ltd. ("Kosmos" or the "Company") (NYSE: KOS) notes today's announcement by Tullow Oil plc ("Tullow") (LSE: TLW) regarding a potential transaction involving Tullow and Kosmos and confirms that it is in very preliminary discussions with Tullow regarding a possible all-share offer by Kosmos for Tullow.

There can be no certainty that any offer will be made, nor as to the terms on which any offer might be made. Pursuant to Rule 2.5 of the Code, Kosmos reserves the right to vary the form and/or mix of the offer consideration and vary the transaction structure. A further announcement will be made as and when appropriate.

As stated in today's announcement by Tullow, in accordance with Rule 2.6(a) of the Code, Kosmos is required, by not later than 5.00 p.m. on 9 January 2025, to either announce a firm intention to make an offer for Tullow in accordance with Rule 2.7 of the Code or announce that it does not intend to make an offer, in which case the announcement will be treated as a statement to which Rule 2.8 of the Code applies. This deadline can be extended with the consent of the Takeover Panel in accordance with Rule 2.6(c) of the Code.

ENQUIRIES

ABOUT KOSMOS

Kosmos is a full-cycle deepwater, independent oil and gas exploration and production company focused along the offshore Atlantic Margins. Our key assets include production offshore Ghana, Equatorial Guinea and the U.S. Gulf of Mexico, as well as a world-class gas development offshore Mauritania and Senegal. We also pursue a proven basin exploration program in Equatorial Guinea, Ghana and the U.S. Gulf of Mexico. Kosmos is listed on the New York Stock Exchange and London Stock Exchange and is traded under the ticker symbol KOS. As an ethical and transparent company, Kosmos is committed to doing things the right way. The Company's Business Principles articulate our commitment to transparency, ethics, human rights, safety and the environment. Read more about this commitment in our Corporate Responsibility Report. For additional information, visit www.kosmosenergy.com.

PUBLICATION ON A WEBSITE

In accordance with Rule 26.1 of the Code, a copy of this announcement will be made available on www.kosmosenergy.com no later than 12 noon (London time) on the business day following the date of this announcement. The content of the website referred to above is not incorporated into and does not form part of this announcement.

The person responsible for arranging for the release of this announcement on behalf of Kosmos is Josh Marion.

RULE 2.4 INFORMATION

In accordance with Rule 2.4(c)(iii) of the Code, Kosmos confirms that it is not aware of any dealings in Tullow shares that would require a minimum level, or particular form, of consideration that it would be obliged to offer under Rule 6 or Rule 11 of the Code (as appropriate). However, it has not been practicable for Kosmos to make enquiries of all persons presumed to be acting in concert with it prior to this announcement in order to confirm whether any details are required to be disclosed under Rule 2.4(c)(iii). To the extent that any such details are identified following such enquiries, Kosmos will make an announcement disclosing such details as soon as practicable, and in any event by no later than the time it is required to make its Opening Position Disclosure under Rule 8.1 of the Code.

RULE 2.9 INFORMATION

In accordance with Rule 2.9 of the Code, Kosmos confirms that, as at close of business on 12 December 2024 (being the business day prior to the date of this announcement), its issued share capital consisted of 471,816,671 ordinary shares with a par value of $0.01 each in the capital of Kosmos which carry voting rights of one vote per share and admitted to trading on the New York Stock Exchange and London Stock Exchange with International Securities Identification Number ("ISIN") US5006881065.

IMPORTANT NOTICES

Evercore Partners International LLP ("Evercore"), which is authorised and regulated by the Financial Conduct Authority in the UK, is acting exclusively as financial adviser to Kosmos and no one else in connection with the matters described in this announcement and will not be responsible to anyone other than Kosmos for providing the protections afforded to clients of Evercore nor for providing advice in connection with the matters referred to herein. Neither Evercore nor any of its subsidiaries, branches or affiliates owes or accepts any duty, liability, or responsibility whatsoever (whether direct or indirect, whether in contract, in tort, under statute or otherwise) to any person who is not a client of Evercore in connection with this announcement, any statement contained herein, any offer or otherwise. Apart from the responsibilities and liabilities, if any, which may be imposed on Evercore by the Financial Services and Markets Act 2000 and successor legislation, or the regulatory regime established thereunder, or under the regulatory regime of any jurisdiction where exclusion of liability under the relevant regulatory regime would be illegal, void or unenforceable, neither Evercore nor any of its affiliates accepts any responsibility or liability whatsoever for the contents of this announcement, and no representation, express or implied, is made by it, or purported to be made on its behalf, in relation to the contents of this announcement, including its accuracy, completeness or verification of any other statement made or purported to be made by it, or on its behalf, in connection with Kosmos or the matters described in this announcement. To the fullest extent permitted by applicable law, Evercore and its affiliates accordingly disclaim all and any responsibility or liability whether arising in tort, contract or otherwise (save as referred to above) which they might otherwise have in respect of this announcement, or any statement contained herein.

DISCLOSURE REQUIREMENTS OF THE CODE

Under Rule 8.3(a) of the Code, any person who is interested in 1 per cent. or more of any class of relevant securities of an offeree company or of any securities exchange offeror (being any offeror other than an offeror in respect of which it has been announced that its offer is, or is likely to be, solely in cash) must make an Opening Position Disclosure following the commencement of the offer period and, if later, following the announcement in which any securities exchange offeror is first identified.

An Opening Position Disclosure must contain details of the person's interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s). An Opening Position Disclosure by a person to whom Rule 8.3(a) applies must be made by not later than 3.30 pm (London time) on the 10^th business day following the commencement of the offer period and, if appropriate, by not later than 3.30 pm (London time) on the 10^th business day following the announcement in which any securities exchange offeror is first identified. Relevant persons who deal in the relevant securities of the offeree company or of a securities exchange offeror prior to the deadline for making an Opening Position Disclosure must instead make a Dealing Disclosure.

Under Rule 8.3(b) of the Code, any person who is, or becomes, interested in 1 per cent. or more of any class of relevant securities of the offeree company or of any securities exchange offeror must make a Dealing Disclosure if the person deals in any relevant securities of the offeree company or of any securities exchange offeror. A Dealing Disclosure must contain details of the dealing concerned and of the person's interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s), save to the extent that these details have previously been disclosed under Rule 8. A Dealing Disclosure by a person to whom Rule 8.3(b) applies must be made by not later than 3.30 pm (London time) on the business day following the date of the relevant dealing.

If two or more persons act together pursuant to an agreement or understanding, whether formal or informal, to acquire or control an interest in relevant securities of an offeree company or a securities exchange offeror, they will be deemed to be a single person for the purpose of Rule 8.3.

Opening Position Disclosures must also be made by the offeree company and by any offeror and Dealing Disclosures must also be made by the offeree company, by any offeror and by any persons acting in concert with any of them (see Rules 8.1, 8.2 and 8.4 of the Code).

Details of the offeree and offeror companies in respect of whose relevant securities Opening Position Disclosures and Dealing Disclosures must be made can be found in the Disclosure Table on the Takeover Panel's website at www.thetakeoverpanel.org.uk, including details of the number of relevant securities in issue, when the offer period commenced and when any offeror was first identified. You should contact the Panel's Market Surveillance Unit on +44 (0)20 7638 0129 if you are in any doubt as to whether you are required to make an Opening Position Disclosure or a Dealing Disclosure.