Company: RIG
Filing Date: 2025-09-24
Form Type: 424B5
Source: 0001451505-25-000097
Chunk: 56

Company: Transocean Ltd.
Filing Date: 2025-09-24
Form: 424B5
Chunk 56
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.L.P., Houston, Texas, as to certain legal matters relating to U.S. law. Certain legal matters in connection with this offering relating to U.S. law will be passed upon for the underwriters by Vinson & Elkins L.L.P., Houston, Texas.

### EXPERTS
The consolidated financial statements of Transocean Ltd. and subsidiaries appearing in Transocean Ltd.’s Annual Report (Form 10-K) for the year ended December 31, 2024 (including the schedule appearing therein), and the effectiveness of Transocean Ltd.’s internal control over financial reporting as of December 31, 2024, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

### WHERE YOU CAN FIND MORE INFORMATION
We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a website at www.sec.gov where you can access reports, proxy information and registration statements, and other information regarding issuers that file electronically. The shares are listed on the NYSE under the symbol “RIG.” We also maintain an Internet website at www.deepwater.com, which provides additional information about us through which you can also access our SEC filings. Except for the documents incorporated by reference into this prospectus supplement as described under the heading “Incorporation by Reference,” the information and other content contained on our website are not incorporated by reference, do not constitute part of this prospectus supplement and should not be relied upon in connection with making any investment in our shares.

This prospectus supplement and the accompanying base prospectus are part of a registration statement on Form S-3 (File No. 333-280617) that we filed with the SEC. This prospectus supplement and the accompanying base prospectus do not contain all of the information set forth in the registration statement and the exhibits thereto. You may obtain the full registration statement from the SEC or us (as described below). Forms of the documents establishing the terms of the shares are or may be filed as exhibits to the registration statement or documents incorporated by reference in the registration statement. Statements in this prospectus supplement are qualified in all respects by reference to the documents to which they refer. You should refer to the actual documents for a more complete description of the relevant matters.

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