We are excited to invite you to attend the extraordinary general meeting of shareholders (the “Transocean Extraordinary General Meeting”) of Transocean Ltd. (“Transocean”) and the special court-ordered meeting (the “Valaris Court Meeting”) of Valaris Limited (“Valaris”) to approve the proposed business combination between the two companies.

The Transocean Extraordinary General Meeting will be held on November 24, 2026 at 3:00 p.m. Swiss time at the offices of Transocean, Turmstrasse 30, 6312 Steinhausen, Switzerland, and the Valaris Court Meeting will be held on November 24, 2026 at 10:00 a.m. (Bermuda time) at Richmond House, 12 Par-la-ville Road, Hamilton, Bermuda.

On February 9, 2026, Transocean and Valaris entered into a Business Combination Agreement (the “Business Combination Agreement”), a copy of which is attached as Appendix A to the accompanying joint proxy statement (the “Joint Proxy Statement”), providing for their combination (the “Business Combination”), pursuant to which Transocean will acquire all of the issued and outstanding common shares of Valaris, par value $0.01 per share (each, a “Valaris Share” and collectively, the “Valaris Shares”). Subject to the terms and conditions set forth in the Business Combination Agreement, each Valaris Share issued and outstanding immediately prior to the effective time of the Business Combination (the “Effective Time”) (other than Valaris Shares owned by (A) Valaris as treasury shares or owned by any subsidiary of Valaris or (B) Transocean or any subsidiary of Transocean) is expected to be exchanged for 15.235 registered shares of Transocean, par value $0.10 per share (each, a “Transocean Share” and collectively, the “Transocean Shares”), subject to customary adjustments prior to the Effective Time, in accordance with the terms of the Business Combination Agreement. No fractional Transocean Shares will be issued in connection with the Business Combination. Holders of Valaris Shares (the “Valaris Shareholders”) will receive cash in lieu of any fractional Transocean Shares.

The Business Combination will be effected by way of a court-sanctioned scheme of arrangement (“Scheme of Arrangement”) between Valaris and the Valaris Shareholders pursuant to section 99 of the Companies Act 1981 of Bermuda, as amended (the “Companies Act”), a copy of which is attached as Appendix B to the accompanying Joint Proxy Statement, together with the related share capital increases of Transocean to create the new Transocean Shares required to be issued pursuant to the Business Combination. Following consummation of the Business Combination and the share capital increases of Transocean, Valaris will become a wholly-owned subsidiary of Transocean (the “Combined Company”), with Transocean’s existing shareholders and Valaris’ existing shareholders expected to own approximately 53% and 47% of the Combined Company, respectively, on a fully diluted basis (assuming conversion of Transocean’s exchangeable bonds due 2029 into Transocean Shares).

At the Transocean Extraordinary General Meeting, holders of Transocean Shares (collectively, the “Transocean Shareholders”) will, among other things, be asked to consider and to approve:

Transocean is also asking Transocean Shareholders to vote on a proposal unrelated to the Business Combination to remove an obsolete provision (Article 38) from, and make related changes to, the Transocean Articles, as further described in the shareholders’ resolution set forth in Appendix E to the accompanying Joint Proxy Statement (the “Additional Transocean Resolution,” and, together with each of the Share Issuance Resolutions, the NYSE 20% Share Issuance Proposal and the Election Resolutions, the “Transocean Resolutions”). Article 38 of the Transocean Articles permitted a temporary increase in the maximum number of directors through the completion of Transocean’s 2015 annual general meeting and is no longer operative. The Additional Transocean Resolution is unrelated to the Business Combination, and approval of the Additional Transocean Resolution is not a condition to the consummation of the Business Combination Agreement.

At the Valaris Court Meeting, Valaris Shareholders will be asked to vote on the following items:

The Transocean Board UNANIMOUSLY recommends that Transocean Shareholders vote FOR each of the Transocean Resolutions. Please note that approval by Transocean Shareholders of each of the Share Issuance Resolutions and the NYSE 20% Share Issuance Proposal are a condition to the consummation of the Business Combination Agreement. Further, unless all of the Transocean Ordinary Share Capital Increase Resolution, the Transocean Capital Band Resolution and the NYSE 20% Share Issuance Proposal are approved by Transocean Shareholders at the Transocean Extraordinary General Meeting, none of these resolutions or the elections under the Election Resolutions will become effective, even if approved by Transocean Shareholders at the Transocean Extraordinary General Meeting. For more details, see the section entitled “Resolutions Submitted to Transocean Shareholders” beginning on page 67 of the accompanying Joint Proxy Statement and the full text of the shareholders’ resolutions in Appendices C, D and E, respectively, to the accompanying Joint Proxy Statement.

The board of directors of Valaris UNANIMOUSLY recommends that Valaris Shareholders vote FOR each of the Valaris Meeting Proposals. Please note that approval by Valaris Shareholders of the Valaris Transaction Resolution is a condition to the consummation of the Business Combination Agreement. For more details and the full text of the resolutions for the Valaris Meeting Proposals, see the section entitled “Proposals Submitted to Valaris Shareholders” beginning on page 57 of the accompanying Joint Proxy Statement.

YOUR VOTE IS IMPORTANT. Whether or not you expect to attend the Transocean Extraordinary General Meeting or the Valaris Court Meeting in person or by proxy, as applicable, please submit your vote as soon as possible. Valaris and Transocean urge you to read the enclosed materials carefully and to promptly vote by following the instructions in the enclosed materials.

The accompanying Joint Proxy Statement contains a detailed description of the Transocean Extraordinary General Meeting, the Valaris Court Meeting and the Scheme of Arrangement, as well as detailed information regarding Transocean and Valaris, and certain pro forma information regarding the Combined Company after giving effect to the Business Combination. Please read this information, including the risk factors discussed in the “Risk Factors” section beginning on page 42 of the accompanying Joint Proxy Statement, carefully, and if you require assistance, consult your own legal, tax, financial or other professional advisor.

The accompanying Joint Proxy Statement is dated October 13, 2026, and is first being mailed to Transocean Shareholders and Valaris Shareholders on or about October 14, 2026.

Neither the United States Securities and Exchange Commission nor any state securities regulatory agency has approved or disapproved the transactions contemplated by the Business Combination Agreement (including the Business Combination), passed upon the merits or fairness of the transactions contemplated by the Business Combination Agreement (including the Business Combination) or passed upon the adequacy or accuracy of the disclosure in the accompanying Joint Proxy Statement. Any representation to the contrary is a criminal offense.

NOTICE IS HEREBY GIVEN that, pursuant to an order of the Supreme Court of Bermuda (the ”Court”) dated August 7, 2026 (the “Interim Order”), a special general meeting (the “Valaris Court Meeting”) of holders (“Valaris Shareholders”) of common shares, par value $0.01 per share (“Valaris Shares”) of Valaris Limited (“Valaris”) will be held on November 24, 2026 at 10:00 a.m. (Bermuda time) at Richmond House, 12 Par-la-ville Road, Hamilton, Bermuda.

On February 9, 2026, Transocean Ltd. (“Transocean”) and Valaris entered into a Business Combination Agreement (the “Business Combination Agreement”), a copy of which is attached as Appendix A to the accompanying joint proxy statement (the “Joint Proxy Statement”), providing for their combination (the “Business Combination”), pursuant to which Transocean will acquire all of the issued and outstanding Valaris Shares. Subject to the terms and conditions set forth in the Business Combination Agreement, each Valaris Share issued and outstanding immediately prior to the effective time of the Business Combination (the “Effective Time”) (other than Valaris Shares owned by (A) Valaris as treasury shares or owned by any subsidiary of Valaris or (B) Transocean or any subsidiary of Transocean) is expected to be exchanged for 15.235 registered shares of Transocean, par value $0.10 per share (each, a “Transocean Share” and collectively, the “Transocean Shares”), subject to customary adjustments prior to the Effective Time, in accordance with the terms of the Business Combination Agreement. No fractional Transocean Shares will be issued to Valaris Shareholders in connection with the Business Combination, and Valaris Shareholders will receive cash in lieu of any fractional Transocean Shares.

The Business Combination will be effected by way of a court-sanctioned scheme of arrangement (“Scheme of Arrangement”) between Valaris and the Valaris Shareholders pursuant to section 99 of the Companies Act 1981 of Bermuda, as amended (the “Companies Act”), a copy of which is attached as Appendix B to the accompanying Joint Proxy Statement, together with the related share capital increases of Transocean to create the new Transocean Shares required to be issued pursuant to the Business Combination. Following consummation of the Business Combination and the share capital increases of Transocean, Valaris will become a wholly-owned subsidiary of Transocean (the “Combined Company”), with Transocean’s existing shareholders and Valaris’ existing shareholders expected to own approximately 53% and 47% of the Combined Company, respectively, on a fully diluted basis (assuming conversion of Transocean’s exchangeable bonds due 2029 into Transocean Shares).

At the Valaris Court Meeting, Valaris will ask the Valaris Shareholders to vote on the following items :

For more details and the full text of the resolutions for the Valaris Meeting Proposals, see the section entitled “Proposals Submitted to Valaris Shareholders” beginning on page 57 of the accompanying Joint Proxy Statement.

Valaris is sending this Notice of Valaris Court Meeting, the accompanying Joint Proxy Statement and its appendices to all Valaris Shareholders of record as of the close of business on October 9, 2026 (the “Valaris Notice Record Date”).

Only Valaris Shareholders of record whose names have been entered into the register of Valaris Shareholders maintained by Valaris’ share registrar and transfer agent, Computershare Trust Company, N.A. (the “Valaris Transfer Agent”), as of the close of business on November 9, 2026 (the “Valaris Voting Record Date”) are entitled to attend and vote at the Valaris Court Meeting. If you are a beneficial owner of Valaris Shares but not a Valaris Shareholder of record (i.e., the legal, registered holder) and wish to attend the Valaris Court Meeting and vote your Valaris Shares directly in your own name, you must become a registered holder by the Valaris Voting Record Date. Beneficial owners of Valaris Shares (those who hold Valaris Shares in “street name”) as of the Valaris Voting Record Date should follow the instructions on their enclosed voting instruction form(s) or contact their broker, bank or other nominee for further instructions on how they can instruct such intermediary to vote on their behalf at the Valaris Court Meeting and the date by which they must provide instructions to such intermediary.

As soon as reasonably practicable following the Valaris Voting Record Date, Valaris anticipates sending a copy of this Notice of Valaris Court Meeting, the accompanying Joint Proxy Statement and its appendices to all Valaris Shareholders of record as of the Valaris Voting Record Date who were not Valaris Shareholders of record as of the Valaris Notice Record Date.

If you are a Valaris Shareholder as of the date of the Valaris Notice Record Date but cease to be a Valaris Shareholder as of close of business on the Valaris Voting Record Date and you previously submitted a proxy, such proxy will not be counted.

Valaris Shareholders are not entitled to dissenters’ rights in connection with the Business Combination. A copy of the Scheme of Arrangement is set forth in Appendix B to the accompanying Joint Proxy Statement. A copy of the order of the Court dated August 7, 2026 (the “Interim Order”) is set forth in Appendix F to the accompanying Joint Proxy Statement.

The Joint Proxy Statement which accompanies this Notice of Valaris Court Meeting explains, among other things, the effect of the Scheme of Arrangement and, together with the other information contained in the accompanying Joint Proxy Statement, constitutes the explanatory statement in respect of the Scheme of Arrangement as required by the Companies Act.

Accordingly, in addition to the information contained in this Notice of Valaris Court Meeting, Valaris urges you to carefully read the entire accompanying Joint Proxy Statement and its appendices, including the Business Combination Agreement and the Scheme of Arrangement, and the documents referred to or incorporated by reference in the accompanying Joint Proxy Statement.

The transaction is to be implemented by means of a Scheme of Arrangement between Valaris and Valaris Shareholders sanctioned by the Court of Bermuda (the “Court”) under Part VII of the Companies Act. Implementation of the Scheme of Arrangement requires approval of the Scheme of Arrangement by the Valaris Shareholders at the Valaris Court Meeting. The Scheme of Arrangement also requires the sanction of the Court. The Scheme of Arrangement is set out in full in Appendix B to the accompanying Joint Proxy Statement.

The purpose of the Scheme of Arrangement is to provide for Transocean to acquire the entire issued and outstanding share capital of Valaris. This is to be achieved by Transocean acquiring the Valaris Shares held by Valaris Shareholders as at the Effective Time, in consideration for which Transocean will issue new Transocean Shares to Valaris Shareholders on the basis set out in the Scheme of Arrangement.

Subject to the terms and conditions set forth in the Business Combination Agreement, each Valaris Share issued and outstanding immediately prior to the Effective Time (other than Valaris Shares owned by (A) Valaris as treasury shares or owned by any subsidiary of Valaris or (B) Transocean or any subsidiary of Transocean) is expected to be exchanged for 15.235 Transocean Shares, subject to customary adjustments prior to the Effective Time, in accordance with the terms of the Business Combination Agreement. No fractional Transocean Shares will be issued to Valaris Shareholders in connection with the Business Combination, and Valaris Shareholders will receive cash in lieu of any fractional Transocean Shares.

The Scheme of Arrangement, if approved at the Valaris Court Meeting (or any postponement or adjournment thereof), will not become effective until the satisfaction of all conditions set forth in the Business Combination Agreement, including the sanction by order of the Court (the “Sanction Order”) and the delivery of the Sanction Order for registration to the Registrar of Companies of Bermuda appointed under section 3 of the Companies Act.

By the Interim Order, the Court has appointed Ms. Elizabeth D. Leykum to act as Chair of the Valaris Court Meeting and alternatively, Mr. Anton Dibowitz, will act as Chair of the Valaris Court Meeting in the event that Ms. Leykum is unable to do so. If neither Ms. Leykum nor Mr. Dibowitz are able to act as Chair of the Valaris Court Meeting, the board of directors of Valaris (the “Valaris Board”) has authorized Mr. Davor Vukadin to be the Chair of the Valaris Court Meeting in accordance with the Interim Order. The Chair will report the results of the Valaris Court Meeting to the Court.

The Valaris Board has unanimously approved the Business Combination Agreement and determined that the Business Combination Agreement and the transactions contemplated thereby, including the Scheme of Arrangement, are advisable and in the best interest of Valaris and the Valaris Shareholders.

The Valaris Board unanimously recommends that Valaris Shareholders vote FOR the Valaris Transaction Resolution, FOR the Valaris Advisory Compensation Proposal and FOR the Valaris Adjournment Proposal.

The approval of the Valaris Transaction Resolution requires the affirmative vote of a majority in number of Valaris Shareholders present and voting either in person or by proxy at the Valaris Court Meeting (the “Numerosity Requirement”) representing at least 75% in value (the “Value Requirement”) of the Valaris Shares present and voting either in person or by proxy at the Valaris Court Meeting. If you are a Valaris Shareholder of record as of the close of business on the Valaris Voting Record Date, you will be counted as one shareholder for the Numerosity Requirement and all of the Valaris Shares you vote will be counted for the Value Requirement. If you hold your Valaris Shares in “street name” through a broker, bank or other nominee, then you are a beneficial owner and you will not be counted for the Numerosity Requirement (unless you become a shareholder of record as of the close of business on the Valaris Voting Record Date), but all of the Valaris Shares you vote will be counted for the Value Requirement. Abstentions, failures to vote and broker non-votes are not considered votes cast and will have no effect on the outcome of any of the proposals.

If you are a Valaris Shareholder of record as of the close of business on the Valaris Voting Record Date and plan to attend the Valaris Court Meeting, please bring this Notice of Valaris Court Meeting as your proof of ownership of Valaris Shares.

If you are a beneficial owner of Valaris Shares and hold your Valaris Shares in “street name” through a broker, bank or other nominee, then as a matter of Bermuda law your name is not automatically entered into the register of Valaris Shareholders maintained by the Valaris Transfer Agent and you will not be able to attend or vote in person at the Valaris Court Meeting. If you are a beneficial owner of Valaris Shares and you wish to attend and vote directly (i.e., in your own name) at the Valaris Court Meeting, then you must either (i) become a shareholder of record prior to the Valaris Voting Record Date by registering your Valaris Shares in your own name prior to the Valaris Voting Record Date, or (ii) obtain a “legal proxy,” executed in your favor, from your broker, bank or other nominee (which may take several business days) and submit such “legal proxy” with your ballot at the Valaris Court Meeting. If you wish to become a shareholder of record prior to the Valaris Voting Record Date, please promptly contact your broker, bank or other nominee for further instructions on how to become a shareholder of record.

Your vote is very important regardless of the number of Valaris Shares that you own. If you fail to return your validly executed proxy, vote by telephone or through the internet or attend the Valaris Court Meeting and vote thereat, your Valaris Shares will not be voted.

Whether or not you are able to attend the Valaris Court Meeting, Valaris requests that you authorize a proxy to vote your Valaris Shares either by telephone or through the Internet by following the instructions on the enclosed proxy card or voting instruction form, or completing, signing, dating and returning the enclosed proxy card or voting instruction form by mail in the pre-addressed, postage-paid envelope as promptly as possible. If the telephone or Internet option is available to you, Valaris strongly encourages you to use it because it is faster and less costly. Telephone and Internet voting are available 24 hours a day until 11:59 p.m., Eastern Time, on November 23, 2026, the day immediately prior to the Valaris Court Meeting.

Please note, if you received a voting instruction form and you hold your Valaris Shares through a broker, bank or other nominee, you must provide your instructions to your broker, bank or other nominee as specified in the voting instruction form by the deadline set out therein (which may be an earlier time than set out above). Beneficial owners of Valaris Shares should follow the instructions on their enclosed voting instruction forms or contact their broker, bank or other nominee for further instructions on how they can instruct such intermediary to vote on their behalf at the Valaris Court Meeting and the date by which they must provide instructions to such intermediary. Valaris reserves the right to accept late proxies and to waive the share voting cut-off time, with or without notice, but is under no obligation to accept or reject any particular late proxy.

The accompanying Joint Proxy Statement provides you with more detailed information about the Valaris Court Meeting, the Business Combination Agreement and the transactions contemplated thereby, including the Scheme of Arrangement. Valaris encourages you to carefully read the entire accompanying Joint Proxy Statement and its appendices, including the Business Combination Agreement, Scheme of Arrangement and the documents referred to or incorporated by reference in the accompanying Joint Proxy Statement. You may also obtain additional information about Valaris from other documents Valaris has filed with the U.S. Securities and Exchange Commission (the “SEC”). In particular, you should read the “Risk Factors” section in Valaris’ Annual Report on Form 10-K for the year ended December 31, 2025, and other risk factors detailed from time to time in Valaris’ reports filed with the SEC and incorporated by reference in the accompanying Joint Proxy Statement, for risks relating to Valaris’ business and for a discussion of the risks that you should consider in evaluating the proposed Scheme of Arrangement, the Business Combination Agreement and the transactions contemplated thereby and how they may affect you.

If you have any questions or need assistance submitting your proxy, or if you need additional copies of the accompanying Joint Proxy Statement or the enclosed proxy card or voting instructions, please contact Valaris’ proxy solicitor, Innisfree M&A Incorporated:

NOTICE IS HEREBY GIVEN that an extraordinary general meeting (the “Transocean Extraordinary General Meeting”) of shareholders of registered shares (“Transocean Shareholders”) of Transocean Ltd., a Swiss corporation (“Transocean”), will be held at the offices of Transocean, Turmstrasse 30, 6312 Steinhausen, Switzerland, on November 24, 2026, at 3:00 p.m. Swiss time.

On February 9, 2026, Transocean and Valaris Limited (“Valaris”) entered into a Business Combination Agreement (the “Business Combination Agreement”), a copy of which is attached as Appendix A to the accompanying joint proxy statement (the “Joint Proxy Statement”), providing for their combination (the “Business Combination”), pursuant to which Transocean will acquire all of the issued and outstanding common shares of Valaris, par value $0.01 per share (each, a “Valaris Share” and collectively, the “Valaris Shares”). Subject to the terms and conditions set forth in the Business Combination Agreement, each Valaris Share issued and outstanding immediately prior to the effective time of the Business Combination (the “Effective Time”) (other than Valaris Shares owned by (A) Valaris as treasury shares or owned by any subsidiary of Valaris or (B) Transocean or any subsidiary of Transocean) is expected to be exchanged for 15.235 registered shares of Transocean, par value $0.10 per share (each, a “Transocean Share” and collectively, the “Transocean Shares”), subject to customary adjustments prior to the Effective Time, in accordance with the terms of the Business Combination Agreement. No fractional Transocean Shares will be issued in connection with the Business Combination. Holders of Valaris Shares (the “Valaris Shareholders”) will receive cash in lieu of any fractional Transocean Shares.

The Business Combination will be effected by way of a court-sanctioned scheme of arrangement (“Scheme of Arrangement”) between Valaris and the Valaris Shareholders pursuant to section 99 of the Companies Act 1981 of Bermuda, as amended (the “Companies Act”), a copy of which is attached as Appendix B to the accompanying Joint Proxy Statement, together with the related share capital increases of Transocean to create the new Transocean Shares required to be issued pursuant to the Business Combination. Following consummation of the Business Combination and the share capital increases of Transocean, Valaris will become a wholly-owned subsidiary of Transocean (the “Combined Company”), with Transocean’s existing shareholders and Valaris’ existing shareholders expected to own approximately 53% and 47% of the Combined Company respectively, on a fully diluted basis (assuming conversion of Transocean’s exchangeable bonds due 2029 into Transocean Shares).

At the Transocean Extraordinary General Meeting, Transocean will ask you to vote on the following items:

Each of the Share Issuance Resolutions, the NYSE 20% Share Issuance Proposal, the Election Resolutions and the Additional Transocean Resolution are together referred to as the “Transocean Resolutions.”

Please note that approval by Transocean Shareholders of each of the Share Issuance Resolutions and the NYSE 20% Share Issuance Proposal and the satisfaction of the conditions and requirements set forth therein are a condition to the consummation of the Business Combination Agreement. Further, unless all of the Transocean Ordinary Share Capital Increase Resolution, the Transocean Capital Band Resolution and the NYSE 20% Share Issuance Proposal are approved by Transocean Shareholders at the Transocean Extraordinary General Meeting, none of these resolutions or the elections under the Election Resolutions will become effective, even if approved by Transocean Shareholders at the Transocean Extraordinary General Meeting. For more details, see the section entitled “Resolutions Submitted to Transocean Shareholders” beginning on page 67 of the accompanying Joint Proxy Statement and the full text of the shareholders’ resolutions in Appendices C, D and E, respectively, to the accompanying Joint Proxy Statement.

Specific details of the matters proposed to be put before the Transocean Extraordinary General Meeting are set forth in the accompanying Joint Proxy Statement, which accompanies this Notice of Extraordinary General Meeting of Transocean Shareholders (“Notice of Transocean Extraordinary General Meeting”). A copy of the Business Combination Agreement is attached as Appendix A to the accompanying Joint Proxy Statement and is available for inspection by Transocean Shareholders on the U.S. Securities and Exchange Commission website at www.sec.gov under Transocean’s SEC profile.

A copy of the Notice of Transocean Extraordinary General Meeting is being sent to each Transocean Shareholder registered in Transocean’s share register as of the close of business on October 9, 2026. Any additional Transocean Shareholders who are registered in Transocean’s share register as of the close of business on November 9, 2026 will receive a copy of the accompanying Joint Proxy Statement, including a proxy card. Transocean Shareholders not registered in Transocean’s share register as of November 9, 2026, will not be entitled to vote or grant proxies to vote at the Transocean Extraordinary General Meeting. While no Transocean Shareholder will be entered in Transocean’s share register as a shareholder with voting rights between the close of business on November 9, 2026, and the opening of business on the day following the Transocean Extraordinary General Meeting, share blocking and re-registration are not requirements for any Transocean Shares to be voted at the Transocean Extraordinary General Meeting, and all Transocean Shares may be traded after the close of business on November 9, 2026. Computershare Inc., which maintains Transocean’s share register, will continue to register transfers of Transocean Shares in the share register in its capacity as transfer agent during this period.

Transocean Shareholders registered in Transocean’s share register as of November 9, 2026, have the right to vote their Transocean Shares at the Transocean Extraordinary General Meeting, or may grant a proxy to vote on each of the Transocean Resolutions in this Notice of Transocean Extraordinary General Meeting and any modification to any agenda item or proposal identified in this Notice of Transocean Extraordinary General Meeting or other matter on which voting is permissible under Swiss law and which is properly presented at the Transocean Extraordinary General Meeting for consideration. Such Transocean Shareholders may designate proxies to vote their Transocean Shares electronically over the internet, by telephone or, if they request that the accompanying Joint Proxy Statement and proxy card be mailed to them, by completing, signing and returning the proxy card enclosed with those materials at the Transocean Extraordinary General Meeting.

Transocean urges you to submit your voting instructions electronically over the internet, by telephone or return the proxy card by mail as soon as possible. All electronic voting instructions or proxy cards must be received no later than 4:00 p.m. Eastern Time on November 23, 2026 (10:00 p.m. Swiss time on November 23, 2026), unless extended by Transocean.

If you have timely submitted electronic voting instructions, telephone instructions or a properly executed proxy card, your Transocean Shares will be voted by the independent proxy in accordance with your instructions. Holders of Transocean Shares who have timely submitted their proxy but have not specifically indicated how to vote their Transocean Shares, will be deemed to have instructed the independent proxy to vote in accordance with the recommendations of the Transocean Board with regard to the items listed in the Notice of Transocean Extraordinary General Meeting. If any modifications to agenda items or proposals identified in this Notice of Transocean Extraordinary General Meeting or other matters on which voting is permissible under Swiss law are properly presented at the Transocean Extraordinary General Meeting for consideration, you will be deemed to have instructed the independent proxy, in the absence of other specific instructions, to vote in accordance with the recommendations of the Transocean Board.

As of the date of the accompanying Joint Proxy Statement, the Transocean Board is not aware of any such modifications or other matters proposed to come before the Transocean Extraordinary General Meeting.

Transocean Shareholders who hold their Transocean Shares in the name of a bank, broker or other nominee should follow the instructions provided by their bank, broker or other nominee for voting their Transocean Shares, including whether they may submit voting instructions by mail, telephone or over the internet.

Transocean Shareholders may grant proxies to any third party. Such third party need not be a Transocean Shareholder.

The Transocean Board unanimously recommends that Transocean Shareholders vote FOR the Transocean Resolutions.

Please note that the approval of Transocean Shareholders of each of the Share Issuance Resolutions and the NYSE 20% Share Issuance Proposal is required in order to complete the Business Combination.

Transocean Shareholders should carefully read the accompanying Joint Proxy Statement, including any documents incorporated by reference, and the appendices in their entirety for more detailed information concerning the Business Combination and the other transactions contemplated by the Business Combination Agreement.

Transocean Shareholders who are planning to provide voting instructions in accordance with the enclosed form of proxy or voting instruction form are encouraged to review the accompanying Joint Proxy Statement carefully before submitting such form.

If you are a Transocean Shareholder and have any questions concerning the Transocean Extraordinary General Meeting, please contact:

A note to Swiss and other European investors: Transocean is incorporated in Switzerland, has issued registered shares and trades on the NYSE; however, unlike some Swiss incorporated companies, share blocking and re-registration are not requirements for any Transocean Shares to be voted at the Transocean Extraordinary General Meeting, and all Transocean Shares may be traded after the close of business on November 9, 2026.

This joint proxy statement (the “Joint Proxy Statement”) is being furnished in connection with the solicitation of proxies by the Board of Directors (the “Transocean Board”) of Transocean Ltd. (“Transocean”) for use at the extraordinary general meeting (the “Transocean Extraordinary General Meeting”) of Transocean shareholders (the “Transocean Shareholders”) of registered shares of Transocean (the “Transocean Shares”), to be held at the date, time and place and for the purposes set forth in the attached Notice of Transocean Extraordinary General Meeting.

This Joint Proxy Statement is also being furnished to holders of shares of common shares (“Valaris Shares”) of Valaris Limited (“Valaris”), a Bermuda exempted company, in connection with the solicitation of proxies by management of Valaris for use at the court-ordered meeting of holders of Valaris Shares (the “Valaris Shareholders” and such meeting, the “Valaris Court Meeting”) to be held at the date, time and place and for the purposes set forth in the attached Notice of Valaris Court Meeting. This Joint Proxy Statement is intended to constitute the explanatory statement required by section 100 of the Companies Act.

The following are some questions that you may have about the combination of Valaris and Transocean (the “Business Combination”), the Transocean Extraordinary General Meeting or the Valaris Court Meeting, and brief answers to those questions. We urge you to read carefully the remainder of this Joint Proxy Statement because the information in this section does not provide all of the information that might be important to you with respect to the Business Combination, the Transocean Extraordinary General Meeting or the Valaris Court Meeting. Additional important information is also contained in the documents incorporated by reference into this Joint Proxy Statement and in the appendices to this Joint Proxy Statement. See the sections entitled “Additional Information Concerning Valaris and Documents Incorporated by Reference by Valaris” beginning on page 203 and “Additional Information Concerning Transocean and Documents Incorporated by Reference by Transocean” beginning on page 205 of this Joint Proxy Statement.

All dates and times are based on Valaris’ and Transocean’s current expectations and are subject to change. Terms used but not defined in this section shall have the meanings given to them in this Joint Proxy Statement. If any of the dates and/or times in this expected timetable change, Valaris and Transocean will publicly announce the changes.

All financial statements and financial data derived therefrom included or incorporated by reference in this Joint Proxy Statement pertaining to Transocean, including the unaudited pro forma condensed combined financial statements of Transocean, have been prepared and presented in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). For further details, see the notes to the unaudited pro forma condensed combined financial statements of Transocean set out in Appendix J to this Joint Proxy Statement.

Pro forma financial information included in this Joint Proxy Statement is for illustrative purposes only and is unaudited. All unaudited pro forma financial information contained in this Joint Proxy Statement has been prepared in accordance with Article 11 of Regulation S-X to illustrate the effect of the Business Combination. The pro forma financial information is not necessarily, and should not be assumed to be, an indication of the actual results of operations and financial position that would have been achieved had Transocean and Valaris operated as a single combined company as, at, or for the periods stated or that may be achieved in the future.

The financial projections provided in this Joint Proxy Statement are for informational purposes only. Such projections were not prepared with a view toward public disclosure or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. The inclusion of the financial projections should not be regarded as an indication that the Transocean Board, management of Transocean, Transocean, the board of directors of Valaris (the “Valaris Board”), management of Valaris, Valaris, their respective advisors or any recipient of this information considered, or now considers, it to be an assurance of the achievement of future results. There can be no assurance that the results reflected in any of the future projections will be realized or that actual results will not materially vary from such projections.

All financial statements and financial data derived therefrom included or incorporated by reference in this Joint Proxy Statement pertaining to Valaris have been prepared and presented in accordance with U.S. GAAP.

THE TRANSOCEAN SHARES TO BE ISSUED IN CONNECTION WITH THE BUSINESS COMBINATION HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SEC OR THE SECURITIES REGULATORY AUTHORITY IN ANY STATE IN THE UNITED STATES, NOR HAVE THE SEC OR THE SECURITIES REGULATORY AUTHORITY OF ANY STATE IN THE UNITED STATES PASSED ON THE ADEQUACY OR ACCURACY OF THIS JOINT PROXY STATEMENT. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

Neither Transocean nor Valaris has authorized any person to give any information or to make any representation in connection with the Scheme of Arrangement or any other matters to be considered at the Transocean Extraordinary General Meeting or the Valaris Court Meeting, other than those contained in this Joint Proxy Statement. If any such information or representation is given or made, such information or representation should not be relied upon as having been authorized or as being accurate. For greater certainty, to the extent that any information provided on either Transocean’s or Valaris’ website or by the proxy solicitation agent is inconsistent with this Joint Proxy Statement, the information provided in this Joint Proxy Statement should be relied upon.

This Joint Proxy Statement does not constitute an offer to buy, or a solicitation of an offer to sell, any securities, or the solicitation of a proxy, by any person in any jurisdiction in which such an offer or solicitation is not authorized, or in which the person making such an offer or solicitation is not qualified to do so, or to any person to whom it is unlawful to make such an offer or solicitation.

Transocean Shareholders and Valaris Shareholders should not construe the contents of this Joint Proxy Statement as legal, tax or financial advice and should consult with their own legal, tax, financial or other professional advisors.

All summaries of, and references to, the Business Combination Agreement, the Scheme of Arrangement, the Transocean Shareholder Support Agreement and the Valaris Shareholder Support Agreements in this Joint Proxy Statement are qualified in their entirety by, in the case of the Business Combination Agreement, the complete text of the Business Combination Agreement, a copy of which is attached as Appendix A to this Joint Proxy Statement and is available on Transocean and Valaris’ respective EDGAR profiles at www.sec.gov, and in the case of the Scheme of Arrangement, the complete text of the Scheme of Arrangement, a copy of which is attached as Appendix B to this Joint Proxy Statement, in the case of the Transocean Shareholder Support Agreement and the Valaris Shareholder Support Agreements, the complete text of each of the Transocean Shareholder Support Agreement and the Valaris Shareholder Support Agreements, available on Transocean and Valaris’ respective EDGAR profiles at www.sec.gov. Transocean Shareholders and Valaris Shareholders are urged to carefully read the full text of the Business Combination Agreement and the Scheme of Arrangement.

This Joint Proxy Statement may contain industry, market and competitive position data from our own internal estimates and research as well as industry and general publications and research surveys and studies conducted by third parties. Industry publications, studies and surveys generally state that they have been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. Our internal data and estimates are based upon information obtained from trade and business organizations and other contacts in the markets in which we operate and our management’s understanding of industry conditions. While we believe that each of these studies and publications is reliable, we have not independently verified market and industry data from third-party sources. While we believe our internal company research is reliable and the market definitions are appropriate, neither such research nor these definitions have been verified by any independent source.

This Joint Proxy Statement is dated October 13, 2026. Information contained in this Joint Proxy Statement is given as of October 13, 2026, unless otherwise specifically stated and except for information contained in documents incorporated by reference herein, which is given as of the respective dates stated in such documents.

This Joint Proxy Statement, including the documents incorporated by reference herein, include “forward-looking statements” within the meaning of the federal securities laws, including, but not limited to, those statements related to the Business Combination, including financial estimates and statements as to the expected timing, completion and effects of the Business Combination. These forward-looking statements are generally identified by the words “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “forecast,” “project,” “might,” “could,” “expect,” “estimate,” “intend,” “strategy,” “plan,” “predict,” “potential,” “may,” “should,” “will,” “would,” “will be,” “will continue,” “will likely result,” and similar expressions, although not all forward-looking statements contain these identifying words.

Any statements about Transocean’s, Valaris’ or the Combined Company’s plans, objectives, expectations, strategies, beliefs or future performance or events constitute forward-looking statements. In addition, any information or statements contained in this Joint Proxy Statement, including the documents incorporated by reference herein, that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the Business Combination and are based on Transocean’s and Valaris’ current expectations, estimates, projections and assumptions. In particular, certain statements included in the sections entitled “Description of the Business Combination — Valaris’ Reasons for the Business Combination and Recommendation of the Valaris Board,” beginning on page 92, “Description of the Business Combination — Transocean’s Reasons for the Business Combination and Recommendation of the Transocean Board” beginning on page 95 and “Risk Factors — Risks Related to the Combined Company “ beginning on page 46 of this Joint Proxy Statement are forward-looking statements.

Because forward-looking statements relate to future events, they are subject to inherent uncertainties, risks and changes in circumstances that may differ materially from those expressed or implied by such statements. Forward-looking statements are neither statements of historical fact nor guarantees or assurances of future performance, including statements regarding the consummation of the Business Combination or the anticipated benefits thereof. There can be no assurance that future events will occur as anticipated or that Transocean’s or Valaris’ results, estimates or assumptions will be realized, and actual results may differ materially from those currently anticipated due to a number of risks and uncertainties, many of which are beyond Transocean’s and Valaris’ control. Accordingly, investors and other readers are cautioned not to place undue reliance on these forward-looking statements.

Any such forward-looking statements include, but are not limited to, statements with respect to:

Important factors, risks and uncertainties that could cause actual results to differ materially from such plans, estimates or expectations include but are not limited to:

There can be no assurance that the Business Combination will be completed, or if it is completed, that it will close within the anticipated time period. While the list of factors presented in this Joint Proxy Statement is considered representative, no such list should be considered to be a complete statement of all potential risks and uncertainties and should be read in conjunction with the other forward-looking statements. Unlisted factors may present significant additional obstacles to the realization of forward-looking statements. The forward-looking statements relate only to events as of the date on which the statements are made and neither Transocean nor Valaris undertake any obligation to update, and expressly disclaim any obligation to update, any forward-looking statements, or any other information in this communication, whether resulting from developments, circumstances or events that arise after the date the statements are made, new information, or otherwise. If one or more of these or other risks or uncertainties materialize, or if Transocean or Valaris’ underlying assumptions prove to be incorrect, actual results may vary materially from what Transocean or Valaris may have expressed or implied by these forward-looking statements. All forward-looking statements in this Joint Proxy Statement are qualified in their entirety by this cautionary statement. You should specifically consider the factors identified in this Joint Proxy Statement that could cause actual results to differ. Furthermore, new risks and uncertainties arise from time to time, and it is impossible for the parties to predict those events or how they may affect Transocean, Valaris or the Combined Company.

The following risk factors should be considered by Transocean Shareholders and Valaris Shareholders in evaluating whether to approve the Transocean Resolutions and the Valaris Meeting Proposals, respectively. These risk factors should be considered in conjunction with the other information contained in or incorporated by reference into this Joint Proxy Statement. These risk factors relate to the Business Combination. For information on risks and uncertainties relating to the business of Transocean, see “Additional Information Concerning Transocean and Documents Incorporated by Reference by Transocean” beginning on page 205 of this Joint Proxy Statement and for information on risks and uncertainties relating to the business of Valaris, see “Additional Information Concerning Valaris and Documents Incorporated by Reference by Valaris” beginning on page 203 of this Joint Proxy Statement.

Following completion of the Business Combination, Valaris Shareholders will no longer be shareholders of Valaris, a Bermuda exempted company, and will instead become shareholders of Transocean, a Swiss corporation. There will be important differences between the current rights of Valaris Shareholders under Bermuda law and the organizational documents of Valaris and the rights to which such shareholders will be entitled as shareholders of Transocean under Swiss law, the Transocean Articles and the organizational regulations of Transocean (the “Transocean Organizational Regulations,” and together with the Transocean Articles, the “Transocean Constitutional Documents”). These differences include, among others, shareholder voting rights, shareholder rights of preemption, procedures related to shareholder meetings, rights to dividends and distributions, share repurchases, and shareholder actions. These differences could be material to Valaris Shareholders. See “Comparison of Shareholder Rights” beginning on page 197 of this Joint Proxy Statement, for a more detailed discussion of the differences between the rights of Valaris Shareholders and Transocean Shareholders.

The completion of the Business Combination is subject to a number of conditions precedent, some of which are outside Valaris’ and Transocean’s control, including, but not limited to: (i) approval of the Valaris Transaction Resolution by the Valaris Shareholders and approval of the Share Issuance Resolutions by the Transocean Shareholders and the registration of the Transocean Shares to be issued pursuant to the Business Combination Agreement with the Commercial Register, (ii) granting of the Sanction Order by the Court on terms consistent with the Business Combination Agreement, (iii) the Transocean Shares issued pursuant to the Business Combination Agreement having been approved for listing on the NYSE, (iv) certain regulatory approvals having been obtained or any applicable waiting period having expired or been terminated, (v) no governmental authority within applicable jurisdictions having enacted or issued any law or order preventing or prohibiting the consummation of the Business Combination and (vi) the absence of a Transocean Material Adverse Effect or a Valaris Material Adverse Effect, each as defined in the Business Combination Agreement. See “Description of the Business Combination — Court Approval” beginning on page 127, “Description of the Business Combination — Stock Exchange Listing” beginning on page 133, and “Description of the Business Combination — Regulatory Approvals — HSR Act Approval” beginning on page 130, and “The Business Combination Agreement — Conditions to Closing of the Business Combination” beginning on page 157 of this Joint Proxy Statement. Therefore, there can be no certainty, nor can Valaris or Transocean provide any assurance, that all conditions precedent to the Business Combination will be satisfied or waived, or, if satisfied or waived, when they will be satisfied or waived and, accordingly, the Business Combination may not be completed. If the Business Combination is not completed, the market price of Valaris Shares and Transocean Shares may be adversely affected in a number of ways, including to the extent that the current market prices of Valaris Shares and Transocean Shares reflect an assumption that the Business Combination will be consummated.

To complete the Business Combination, each of Valaris and Transocean must make certain filings with and obtain certain consents and approvals from various governmental and regulatory authorities.

The Business Combination was subject to review under the HSR Act, and may be subject to review under the antitrust or competition laws of other jurisdictions in which Transocean and Valaris operate. Both Transocean and Valaris are international offshore contract drilling companies with operations across multiple jurisdictions, and the applicable antitrust authorities may scrutinize the competitive effects of the combination of their respective drilling fleets. The regulatory approval processes may take a lengthy period of time to complete, which could delay completion of the Business Combination. If obtained, the Key Regulatory Approvals may be conditioned, with the conditions imposed by the applicable governmental authority going beyond the terms of the Business Combination Agreement or otherwise not being acceptable to either Valaris or Transocean, or, if acceptable, not being on terms that are favorable to the Combined Company. There can be no assurance as to the outcome of the regulatory approval processes, including the undertakings and conditions that may be required for approval or whether the Key Regulatory Approvals will be obtained. If not obtained, or if obtained on terms that are not satisfactory to either Valaris or Transocean, the Business Combination may not be completed.

Pursuant to the terms of the Business Combination Agreement, each of Valaris and Transocean has the right, in certain circumstances, in addition to termination rights relating to the failure to satisfy the conditions of closing, to terminate the Business Combination. If the Business Combination is not completed by twelve months from the date of the Business Combination Agreement (subject to the right of either party to extend such date by up to an additional three months if required regulatory approvals have not been obtained by such date), either Valaris or Transocean may choose to terminate the Business Combination Agreement. Accordingly, there can be no certainty, nor can Valaris or Transocean provide any assurance, that the Business Combination will not be terminated by either of Valaris or Transocean prior to the completion of the Business Combination.

In connection with any such termination, depending on the circumstances, (i) Valaris may be required to pay Transocean a termination fee of $173,000,000, (ii) Transocean may be required to pay Valaris a termination fee of $195,000,000, (iii) if the Business Combination Agreement is terminated due to failure of the Valaris Shareholders to approve the Valaris Transaction Resolution, Valaris may be required to reimburse up to $58,000,000 of Transocean’s transaction expenses, and (iv) if the Business Combination Agreement is terminated due to failure of the Transocean Shareholders to approve the Share Issuance Resolutions, Transocean may be required to reimburse up to $65,000,000 of Valaris’ transaction expenses. These termination-related fees and expense reimbursement obligations may discourage third parties from making competing acquisition proposals with respect to Valaris or Transocean, even if such proposals would otherwise offer greater value to Valaris Shareholders or Transocean Shareholders than the Business Combination. Any termination of the Business Combination Agreement would also result in the failure to realize the anticipated benefits of the Business Combination. See “The Business Combination Agreement — Termination” beginning on page 160, “The Business Combination Agreement — Termination — Termination Fees and Reimbursement Expenses” beginning on page 161 and “The Business Combination Agreement — Termination — Recovery Costs” beginning on page 163 of this Joint Proxy Statement.

Each of Valaris and Transocean has expended, and continues to expend, significant management time and resources in connection with the Business Combination, which may have a negative impact on their respective ongoing businesses and operations. Uncertainty regarding the outcome of the Business Combination may disrupt existing and prospective relationships with customers, suppliers and other business partners, who may attempt to negotiate changes to existing arrangements, consider entering into business relationships with other parties or terminate or amend existing contracts. Such uncertainty may also adversely affect the ability of each of Valaris and Transocean to recruit and retain key personnel and other employees during the pendency of the Business Combination. The pendency of the Business Combination may also result in negative publicity or an adverse

impression of either company in the financial markets, and may give rise to litigation against either company or their respective directors and officers, which could be distracting to management, require the incurrence of significant costs and potentially result in the Business Combination being delayed or enjoined. Each of Valaris and Transocean will also incur significant transaction expenses in connection with the Business Combination regardless of whether it is completed. The occurrence of any of these events, individually or in combination, could have a material adverse effect on the business, financial condition and results of operations of each of Valaris and Transocean.

The Business Combination Agreement contains customary non-solicitation provisions that restrict each of Valaris and Transocean from soliciting, encouraging or facilitating any alternative acquisition proposal from a third-party, providing non-public information to third parties in connection with any such proposal or engaging in discussions regarding alternative acquisition proposals, subject to customary exceptions. Each party is required to convene a meeting of its shareholders to obtain the required shareholder approvals and, subject to certain exceptions, to recommend that their respective shareholders vote in favor of the applicable proposals. Neither party has the ability to terminate the Business Combination Agreement to accept a Superior Proposal, as defined in the Business Combination Agreement. In addition, the Business Combination Agreement subjects each party to restrictions on their respective business activities prior to the Effective Time, including obligations to continue to operate in the ordinary course and not to engage in certain specified transactions or activities without the prior consent of the other party. These restrictions may prevent each of Valaris and Transocean from pursuing attractive business opportunities that arise prior to completion of the Business Combination. Additionally, if the Business Combination Agreement is terminated and either party determines to seek another business combination, there can be no assurance that such party would be able to negotiate a transaction with another party on terms comparable to or better than those of the Business Combination. See “The Business Combination Agreement — Covenants” beginning on page 144 of this Joint Proxy Statement.

The Exchange Ratio is fixed at 15.235 Transocean Shares for each Valaris Share issued and outstanding immediately prior to the Effective Time, and will not be adjusted to reflect fluctuations in the market prices of Valaris Shares or Transocean Shares prior to the Effective Time. The market prices of both companies may fluctuate significantly prior to the Effective Time in response to a variety of factors, including differences between either company’s actual financial or operating results and those expected by investors and analysts, changes in analysts’ projections or recommendations, changes in general economic or market conditions and broad market fluctuations. A decrease in the price of Transocean Shares or an increase in the price of Valaris Shares prior to the Effective Time would each have the effect of reducing the value of the consideration to be received by Valaris Shareholders relative to the value of Valaris Shares at the time the Business Combination Agreement was entered into. Conversely, an increase in the price of Transocean Shares prior to the Effective Time would benefit Valaris Shareholders but would represent a higher effective cost to Transocean Shareholders. Accordingly, historical market prices are not indicative of the market value of the Transocean Shares that Valaris Shareholders will receive at the Effective Time, and there can be no assurance that the trading price of Transocean Shares will not decline following completion of the Business Combination.

Upon completion of the Business Combination, it is estimated that existing Transocean Shareholders and existing Valaris Shareholders will own approximately 53% and 47%, respectively, of the issued and outstanding shares of the Combined Company on a fully diluted basis (assuming conversion of Transocean’s exchangeable bonds due 2029 into Transocean Shares). As a result, each shareholder group will hold a proportionally smaller ownership and voting interest in the Combined Company than they currently hold in their respective companies, and will therefore have a reduced ability to influence the outcome of matters submitted to shareholders for approval,

including the election of directors, amendments to the Combined Company’s organizational documents and other significant corporate transactions. Transocean Shareholders in particular should be aware that as a result of the share issuance in connection with the Business Combination, their individual ownership percentage in Transocean will be diluted. See “Description of the Business Combination — Pro Forma Economic Ownership of the Combined Company” beginning on page 132 of this Joint Proxy Statement.

The directors and executive officers of each of Valaris and Transocean negotiated the terms of the Business Combination Agreement, and each of the Valaris Board and the Transocean Board has unanimously recommended that their respective shareholders vote in favor of the proposals required to complete the Business Combination. These directors and executive officers may have interests in the Business Combination that are different from, or in addition to, those of Valaris Shareholders and Transocean Shareholders generally, including interests arising from compensation arrangements, the accelerated vesting of equity awards, retention arrangements and the expectation that certain directors and officers will serve in leadership roles in the Combined Company following the Effective Time. Each of the Valaris Board and the Transocean Board was aware of, and considered, these interests when declaring the advisability of the Business Combination Agreement and unanimously recommending that their respective shareholders vote in favor of the applicable proposals. Valaris Shareholders and Transocean Shareholders should be aware of these interests when considering the recommendations of their respective boards. See “Description of the Business Combination — Interests of Valaris’ Directors and Management in the Business Combination” beginning on page 122, and “Description of the Business Combination — Interests of Transocean’s Directors and Management in the Business Combination” beginning on page 127 of this Joint Proxy Statement.

In order for Transocean to issue the Transocean Shares to be delivered in connection with the Business Combination, including to Valaris Shareholders and the holders of Valaris Incentives, Transocean must register the requisite increases in its share capital and the Transocean Shares to be issued pursuant to the Business Combination Agreement with the Commercial Register. This registration is required for and a condition to the completion of the Business Combination. Under Swiss law, such registration may be blocked or delayed for reasons beyond Transocean’s control, which could delay or prevent the issuance of the Transocean Shares to be delivered to Valaris Shareholders shortly after the Effective Time. Any such delay or failure to complete the required Swiss registration could delay or prevent the completion of the Business Combination, which could have an adverse effect on the business, financial condition and results of operations of each of Valaris and Transocean, as well as on the market price of Valaris Shares and Transocean Shares. See “The Business Combination Agreement — Conditions to Closing of the Business Combination” beginning on page 157 of this Joint Proxy Statement.

Securities class action lawsuits and derivative lawsuits are frequently brought against companies that have entered into merger agreements, and Valaris or Transocean may become subject to this type of litigation in connection with the Business Combination. Even if any such lawsuits are without merit, defending against these claims can be expensive and can divert management’s attention and resources from the operation of their respective businesses, which could have a material adverse effect on the business, financial condition and results of operations of each of Valaris and Transocean. An adverse judgment could result in monetary damages, which could negatively impact the liquidity and financial condition of Valaris, Transocean or the Combined Company. Additionally, if a plaintiff were to obtain an injunction prohibiting the consummation of the Business Combination, such injunction could delay or prevent the Business Combination from being completed entirely. The Combined Company may also become subject to similar litigation following completion of the Business Combination.

The business and operations of the Combined Company will be subject to the risks described in the documents of Valaris and Transocean incorporated by reference in this Joint Proxy Statement, including, without limitation, the risks described in the Valaris’ Annual Report filed on Form 10-K for the year ended December 31, 2025, Transocean’s Annual Report filed on Form 10-K for the year ended December 31, 2025, and any subsequent SEC filings of Valaris or Transocean, and certain unexpected, unforeseen or unknown risks. The Combined Company’s business, financial condition, results of operations and cash flows could be materially adversely affected by any of these risks. The market or trading price of Valaris’ and Transocean’s securities could decline due to any of these risks. Additional risks not presently known to Valaris and Transocean or that Valaris and Transocean currently considers immaterial may also prove to be material and may impair the Combined Company’s business and operations. In addition to risks associated with Valaris’ and Transocean’s business and operations, the following additional risks are associated with the Combined Company.

Valaris and Transocean have operated, and until completion of the Business Combination will continue to operate, as independent companies. Following completion of the Business Combination, the Combined Company will need to integrate two large, complex, globally dispersed offshore drilling businesses, including their respective management structures, operations, personnel, information technology systems, accounting systems, internal controls, compensation programs and other policies and procedures. This integration process will be complex and time-consuming, and the Combined Company may face significant challenges, including identifying and eliminating redundant functions and assets, harmonizing operating practices, minimizing the loss of key employees and maintaining existing relationships with customers, suppliers and other business partners during the transition period.

There can be no assurance that the Combined Company will be able to integrate the businesses of Valaris and Transocean successfully or within the anticipated timeframe, or that the integration will achieve the cost savings and operating synergies that the parties anticipate as a result of the Business Combination. The realization of such benefits may be affected by a number of factors beyond the control of the Combined Company, including general economic and market conditions, competitive factors in the markets in which Valaris and Transocean operate and changes in laws and regulations affecting the offshore drilling industry. If the Combined Company is unable to achieve these objectives, the anticipated benefits and synergies expected from the Business Combination may not be realized, in whole or in part, or may not be realized within the expected timeframe, which could adversely affect the Combined Company’s business, financial condition and operating results, dilute earnings per share and negatively impact the trading price of Transocean Shares.

The unaudited pro forma financial statements contained in this Joint Proxy Statement are presented for illustrative purposes only and may not be indicative of the Combined Company’s financial condition or results of operations following the Business Combination for a number of reasons. For example, the unaudited pro forma financial statements have been derived from the historical financial statements of Valaris and Transocean and certain adjustments and assumptions have been made regarding the Combined Company after giving effect to the Business Combination. The information upon which these adjustments and assumptions have been made is preliminary, and these types of adjustments and assumptions are difficult to make with complete accuracy. Moreover, the unaudited pro forma financial statements do not reflect all costs that are expected to be incurred by the Combined Company in connection with the Business Combination. As a result, the actual financial condition and results of operations of the Combined Company following the Business Combination may not be consistent with, or evident from, these unaudited pro forma financial statements. In addition, the assumptions used in preparing the unaudited pro forma financial information may not prove to be accurate, and other factors may affect the Combined Company’s financial condition or results of operations following the Business Combination. Any potential decline in the Combined Company’s financial condition or results of operations may cause a significant decrease in the trading price of the Transocean Shares.

The Combined Company’s operations will be subject to extensive and evolving laws and regulations, both in the United States and internationally, relating to drilling operations, health and safety, environmental protection, greenhouse gas emissions, trade and sanctions compliance, and the exploration and development of oil and gas. Compliance with these requirements may require significant capital expenditures, operational changes or the installation of costly equipment, and may affect the resale values or useful lives of the Combined Company’s rigs. A failure to comply with applicable laws and regulations could result in administrative or civil penalties, criminal sanctions or the suspension or termination of operations.

Offshore drilling in certain areas has been and may in the future be curtailed or prohibited due to environmental or safety concerns. To the extent new laws are enacted, existing laws are changed or governmental or judicial actions are taken that prohibit or restrict offshore drilling or impose additional environmental protection or safety requirements, the Combined Company’s business or prospects could be materially and adversely affected. In addition, compliance with increasingly stringent environmental and safety regulations, including those relating to greenhouse gas emissions and climate change, may impose additional costs and obligations on the Combined Company and on its customers, which could decrease demand for offshore drilling services, reduce dayrates or limit the areas in which the Combined Company’s rigs may operate.

The Combined Company will also be subject to the laws and regulations of the various international jurisdictions in which it operates, including those relating to trade and economic sanctions, import and export controls, currency exchange restrictions, local content requirements and taxation. Changes to trade policies, including the imposition of additional tariffs or trade barriers, could increase the Combined Company’s operating costs or disrupt its supply chain. Failure to comply with applicable sanctions or trade regulations could subject the Combined Company to criminal sanctions, civil remedies or reputational harm. The laws and regulations governing the Combined Company’s international operations are complex, constantly evolving and may be interpreted or enforced in ways that materially impact its operations.

Any of the foregoing changes in the regulatory environment applicable to the Combined Company’s operations, or the Combined Company’s failure to comply with applicable laws and regulations, could have a material adverse effect on the Combined Company’s business, financial condition, results of operations and cash flows.

As of June 30, 2026, Transocean had total debt of $5.12 billion, of which $1.12 billion was secured. As of June 30, 2026, Valaris had total debt of $1.09 billion. The Combined Company will carry this substantial debt following completion of the Business Combination. This level of indebtedness could have significant adverse consequences, including limiting the Combined Company’s ability to obtain financing in the future for working capital, capital expenditures, acquisitions or other purposes; requiring the dedication of a substantial portion of operating cash flows to debt service, reducing funds available for other business purposes; making the Combined Company more vulnerable to adverse economic and industry conditions, including increases in interest rates; limiting the Combined Company’s ability to take advantage of significant business opportunities or react to changes in market or industry conditions compared to less levered competitors; and creating risk of default under the agreements governing the Combined Company’s credit facilities, which could trigger cross-default provisions across other debt instruments or, in the case of secured debt, result in foreclosure on collateral including applicable drilling units.

In addition, Transocean’s debt is currently rated below investment grade, which could limit the Combined Company’s access to capital markets, result in less favorable terms on any refinancing arrangements, reduce the willingness of customers, suppliers and creditors to transact business with the Combined Company, and require the posting of additional collateral, guarantees or insurance. Any further downgrade to the Combined Company’s debt ratings could exacerbate these effects.

While Transocean has undertaken deleveraging activities in recent periods and the parties anticipate that the Combined Company’s improved cash flow profile will support continued debt reduction following completion of

the Business Combination, there can be no assurance that the Combined Company will be able to reduce its indebtedness on the anticipated timeline or at all. Failure to successfully de-leverage could have a material adverse effect on the Combined Company’s business, financial condition, results of operations and cash flows.

Transocean is a Swiss corporation, and certain of its directors and officers may reside outside the United States. All or a substantial portion of the assets of Transocean and of such persons may be located outside the United States. As a result, it may be difficult for investors to effect service of process within the United States upon such persons or to enforce any judgment obtained in a U.S. court against such persons that is predicated upon the civil liability provisions of U.S. federal securities laws. Swiss legal counsel has advised Transocean that it is uncertain whether Swiss courts would enforce (i) judgments of U.S. courts obtained in actions against Transocean or other persons that are predicated upon the civil liability provisions of U.S. federal securities laws or (ii) original actions brought against Transocean or other persons predicated upon the Securities Act. The enforceability in Switzerland of a foreign judgment rendered against Transocean or such other persons is subject to the limitations set forth in applicable international treaties by which Switzerland is bound and the Swiss Federal Private International Law Act. In particular, a judgment rendered by a foreign court may only be enforced in Switzerland if: (a) such foreign court had jurisdiction; (b) such judgment has become final and non-appealable; (c) the court procedures leading to such judgment followed the principles of due process of law, including proper service of process; and (d) such judgment does not violate Swiss law principles of public policy.

Valaris is a Bermuda exempted company and the rights of Valaris Shareholders are governed by Bermuda law and the Valaris constitutional documents. The rights of shareholders under Bermuda law may differ from the rights of shareholders of companies incorporated in other jurisdictions. Some of Valaris’ directors and officers are not residents of the United States, and a substantial portion of Valaris’ assets are located outside the United States. As a result, it may be difficult for investors to effect service of process on those persons in the United States or to enforce judgments obtained in U.S. courts against Valaris or those persons based on the civil liability provisions of U.S. securities laws. There is no guarantee that courts in Bermuda will enforce judgments obtained in other jurisdictions, including the United States, against Valaris or its directors or officers under the securities laws of such other jurisdictions or entertain actions in Bermuda against Valaris or its directors or officers under the securities laws of such other jurisdictions.

Transocean and Valaris intend that the Business Combination qualify, and have agreed to use reasonable best efforts to cause the Business Combination to qualify, as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code. In general, assuming the Business Combination so qualifies, U.S. Holders (as defined in “Certain U.S. Federal Income Tax Considerations of the Business Combination” beginning on page 170 of this Joint Proxy Statement) of Valaris Shares will not recognize any gain or loss for U.S. federal income tax purposes on the receipt of Transocean Shares in exchange for Valaris Shares pursuant to the Business Combination, except with respect to any cash received in lieu of fractional Transocean Shares. However, the Business Combination’s qualification as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code is not free from doubt, and the requirements for such qualification are complex and subject to legal and factual uncertainties.

The Business Combination is not conditioned upon the receipt of an opinion of counsel regarding the Business Combination’s qualification as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code. Transocean and Valaris have not sought and will not seek any ruling from the Internal Revenue Service (“IRS”) that the Business Combination qualifies as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code. Consequently, there can be no assurance that the IRS will not challenge that the Business Combination so qualifies or that a court would not sustain such a challenge. If the Business Combination fails to qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code, U.S. Holders of Valaris Shares will recognize gain or loss for U.S. federal income tax purposes on the receipt of Transocean Shares in exchange for Valaris Shares pursuant to the Business Combination, as more fully described in the section entitled “Certain U.S. Federal Income Tax Considerations of the Business Combination — U.S. Federal Income Tax

Considerations if the Business Combination Fails to Qualify as a “Reorganization”” beginning on page 172 of this Joint Proxy Statement. U.S. Holders of Valaris Shares should consult with their tax advisors regarding the tax treatment of the Business Combination to them in light of their particular circumstances.

Under Section 382 of the Internal Revenue Code and corresponding provisions of state law, if a corporation undergoes an “ownership change,” which is generally defined as a greater than 50 percentage point change, by value, in its equity ownership by certain shareholders over a three-year period, the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes to offset its post-change income may be limited. Transocean may have experienced ownership changes in the past. The Combined Company may also experience ownership changes in the future as a result of subsequent shifts in the Combined Company’s share ownership, some of which may be outside of the Combined Company’s control. In addition, the Business Combination, if consummated, may also constitute an ownership change (within the meaning of Section 382 of the Internal Revenue Code) for each of Transocean and Valaris which could substantially limit the Combined Company’s ability to use pre-change net operating loss carryforwards and other pre-change tax attributes of Transocean, Valaris, and their respective subsidiaries in a post-change taxable period.

Following the Business Combination, the Combined Company will be subject to changes in applicable tax laws, treaties or regulations in the jurisdictions in which the Combined Company operates and earns income, and such changes could include laws or policies directed toward companies organized in jurisdictions with low tax rates with the intent to increase their tax burden. Several jurisdictions have implemented and continue to implement the Organization for Economic Co-operation and Development Pillar 2 or other tax related provisions that are aimed at preventing base erosion and profit shifting, ensuring income is subject to a minimum level of taxation and preventing treaty misuse. The application of these provisions is not always certain, and jurisdictions are still developing their rules and interpretations with regard to same.

Any material change to tax laws, treaties, regulations or policies, their interpretation or application, or the adoption of new interpretations of existing laws and rulings, in any of the jurisdictions in which the Combined Company operates, is incorporated or resident, could result in a higher effective tax rate on the Combined Company’s worldwide earnings and such change could have a significant adverse effect on the Combined Company’s financial position, results of operations or cash flows.

Transocean and Valaris are and, following the Business Combination, the Combined Company will be subject to tax laws, treaties and regulations in the countries in which each company operates and earns income. Each of Transocean’s and Valaris’ income taxes are based on the applicable tax laws and tax rates in effect in the countries in which such company operates and earns income as well as upon their respective operating structures in these countries. The income tax returns of Transocean and Valaris are subject to review and examination in these jurisdictions, and neither company recognizes the benefit of income tax positions that are not more likely than not to be respected upon challenge by a tax authority. If any tax authority successfully challenges the Combined Company’s operational structure, intercompany pricing policies or the taxable presence of the Combined Company’s key subsidiaries in certain countries; or if the terms of certain income tax treaties are interpreted in a manner that is adverse to the Combined Company’s structure; or if the Combined Company loses a material tax dispute in any country, the Combined Company’s effective tax rate on its worldwide earnings could increase substantially and the Combined Company’s earnings and cash flows from operations could be materially adversely affected. For example, neither Transocean nor Valaris believe they or their non-U.S. subsidiaries, other than those that report a U.S. trade or business or a U.S. permanent establishment, were or are engaged in a trade or business in the U.S. or, if applicable, maintained or maintain a permanent establishment in the U.S. The determination of the

aforementioned, among other things, involves considerable judgment. If the IRS were to disagree, then the Combined Company could be subject to additional U.S. corporate income and branch profits taxes on the portion of the Combined Company’s earnings effectively connected to such U.S. business or, if applicable, attributable to such U.S. permanent establishment during the period in which this was considered to have occurred. If this occurs, the Combined Company’s effective tax rate on worldwide earnings for that period could increase substantially, the Combined Company could be subject to assessments in previously filed returns that remain open to audit and the Combined Company’s earnings and cash flows from operations for that period could be adversely affected.

Each prospective investor should consult with their own tax advisor with respect to the U.S. and non-U.S. income tax considerations of acquiring, holding and disposing of the Transocean Shares, based on each prospective investor’s particular circumstances.

You should read and consider risk factors specific to Valaris’ business that will also affect the Combined Company after the Business Combination. These risks are described in the sections entitled “Risk Factors” in Valaris’ Annual Report on Form 10-K for the fiscal year ended December 31, 2025 and in other documents incorporated by reference into this Joint Proxy Statement. See “Additional Information Concerning Valaris and Documents Incorporated by Reference by Valaris” beginning on page 203 of this Joint Proxy Statement.

You should read and consider risk factors specific to Transocean’s business that will also affect the Combined Company after the Business Combination. These risks are described in the sections entitled “Risk Factors” in Transocean’s Annual Report on Form 10-K for the fiscal year ended December 31, 2025 and in other documents incorporated by reference into this Joint Proxy Statement. See “Additional Information Concerning Transocean and Documents Incorporated by Reference by Transocean” beginning on page 205 of this Joint Proxy Statement.

The Valaris Court Meeting will be held on November 24, 2026 at 10:00 a.m. (Bermuda time) at Richmond House, 12 Par-la-ville Road, Hamilton, Bermuda. Valaris intends to mail this Joint Proxy Statement and the enclosed form of proxy to Valaris Shareholders as of the Valaris Notice Record Date on or about October 14, 2026.

At the Valaris Court Meeting, Valaris Shareholders will be asked:

The Valaris Transaction Resolution, the Valaris Advisory Compensation Proposal, and the Valaris Adjournment Proposal are together referred to as the Valaris Meeting Proposals. Valaris does not intend to call a vote on the Valaris Adjournment Proposal if the Valaris Transaction Resolution is approved by Valaris Shareholders at the Valaris Court Meeting. For more details and the full text of the resolutions for the Valaris Meeting Proposals, see the section entitled “Proposals Submitted to Valaris Shareholders” beginning on page 57 of this Joint Proxy Statement.

The Valaris Board has unanimously approved the Business Combination Agreement and determined that the Business Combination Agreement and the transactions contemplated thereby, including the Scheme of Arrangement, are advisable and in the best interest of Valaris and the Valaris Shareholders.

The approval of the Valaris Transaction Resolution by Valaris Shareholders is required in order to complete the Business Combination.

Valaris Shareholders should carefully read this Joint Proxy Statement, including any documents incorporated by reference, and the appendices in their entirety for more detailed information concerning the Business Combination and the other transactions contemplated by the Business Combination Agreement.

If you are a Valaris Shareholder of record as of the close of business on the Valaris Voting Record Date and plan to attend the Valaris Court Meeting, please bring the Notice of Valaris Court Meeting as your proof of ownership of Valaris Shares.

If you are a beneficial owner of Valaris Shares and hold your Valaris Shares in “street name” through a broker, bank or other nominee, then as a matter of Bermuda law your name is not automatically entered into the register of Valaris Shareholders maintained by the Valaris Transfer Agent and you will not be able to attend or vote in person at the Valaris Court Meeting. If you are a beneficial owner of Valaris Shares and you wish to attend and vote at the Valaris Court Meeting, then you must either (i) become a shareholder of record prior to the Valaris Voting Record Date by registering your Valaris Shares in your own name prior to the Valaris Voting Record Date, or (ii) obtain a “legal proxy,” executed in your favor, from your broker, bank or other nominee (which may take several business days) and submit such “legal proxy” with your ballot at the Valaris Court Meeting. If you wish to become a shareholder of record prior to the Valaris Voting Record Date, please promptly contact your broker, bank or other nominee for further instructions on how to become a shareholder of record or how to obtain a legal proxy.

Please note that no cameras, recording equipment, laptops, tablets, cellular telephones, smartphones or other similar equipment, electronic devices, large bags, briefcases or packages will be permitted in the Valaris Court Meeting, and security measures will be in effect to ensure the safety of attendees. In all cases, you will need a photo ID to gain admission.

Valaris is sending the Notice of Valaris Court Meeting, this Joint Proxy Statement and the appendices hereto to all Valaris Shareholders of record as of the close of business on the Valaris Notice Record Date.

Only Valaris Shareholders of record whose names have been entered into the register of Valaris Shareholders maintained by the Valaris Transfer Agent, as of the close of business on the Valaris Voting Record Date are entitled to attend and vote at the Valaris Court Meeting. If you are a beneficial owner of Valaris Shares but not a Valaris Shareholder of record (i.e., the legal, registered holder) and wish to attend the Valaris Court Meeting and vote your Valaris Shares directly in your own name, you must become a registered holder by the Valaris Voting Record Date. Beneficial owners of Valaris Shares (those who hold Valaris Shares in “street name”) as of the Valaris Voting Record Date should follow the instructions on their enclosed voting instruction form(s) or contact their broker, bank or other nominee for further instructions on how they can instruct such intermediary to vote on their behalf at the Valaris Court Meeting and the date by which they must provide instructions to such intermediary.

As soon as reasonably practicable following the Valaris Voting Record Date, Valaris anticipates sending a copy of the Notice of Valaris Court Meeting, this Joint Proxy Statement and the appendices hereto to all Valaris Shareholders of record as of the Valaris Voting Record Date who were not Valaris Shareholders of record as of the Valaris Notice Record Date.

If you are a Valaris Shareholder as of the date of the Valaris Notice Record Date but cease to be a Valaris Shareholder as of close of business on the Valaris Voting Record Date and you previously submitted a proxy, such proxy will not be voted. If you are a Valaris Shareholder as of the Valaris Voting Record Date but thereafter transfer your Valaris Shares prior to the Valaris Court Meeting, you will retain your right to vote or direct your broker, bank or other nominee on how to vote your Valaris Shares, but the right to receive Transocean Shares in exchange for your Valaris Shares will pass to the person who holds your Valaris Shares as of immediately prior to the Effective Time.

There is no quorum requirement for the Valaris Court Meeting.

Under the Valaris bye-laws, a quorum for a general meeting of Valaris shareholders would ordinarily require the presence, in person or by proxy, of one or more holders of at least 50% of the issued and outstanding Valaris shares entitled to vote at such meeting. However, pursuant to the Interim Order of the Court, this quorum requirement will not apply to the Valaris Court Meeting.

Accordingly, the Valaris Court Meeting may proceed regardless of the number of Valaris Shares represented.

This Joint Proxy Statement is furnished by the Valaris Board in connection with the solicitation of proxies for use at the Valaris Court Meeting to be held on November 24, 2026 at 10:00 a.m. (Bermuda Time) at Richmond House, 12 Par-la-ville Road, Hamilton, Bermuda, and at any postponements or adjournments of the Valaris Court Meeting.

The Valaris Board is soliciting Valaris Shareholders’ proxies on behalf of Valaris. In addition to the use of mail, proxies may be solicited by personal interview, telephone, facsimile, e-mail or otherwise, by Valaris’ directors, officers and other employees. Valaris has engaged Innisfree M&A Incorporated, to assist in the solicitation of proxies for a fee of $50,000, plus reimbursement of out-of-pocket expenses. Valaris also will request persons, firms and corporations holding shares in their names, or in the names of their nominees, that are beneficially owned by others to send or cause to be sent proxy materials to, and obtain proxies from, such beneficial owners of Valaris Shares and will reimburse such holders for their reasonable expenses in so doing.

A proxy statement is a document that the SEC regulations require Valaris to give you when it asks you to sign a proxy designating individuals to vote on your behalf. A proxy is your legal designation of another person to vote the shares you own. The person designated is called a proxy or proxy holder. If you designate someone as your proxy in a written document, that document is also called a proxy or a proxy card. Shareholders are asked to appoint the following persons as proxy holders for the Valaris Court Meeting: Anton Dibowitz, President and Chief Executive Officer, and Davor Vukadin, SVP, General Counsel and Secretary.