Company: RIG
Filing Date: 2025-09-26
Form Type: 424B5
Source: 0001451505-25-000102
Chunk: 102

Company: Transocean Ltd.
Filing Date: 2025-09-26
Form: 424B5
Chunk 102
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 to make. Agents, dealers and underwriters may be our customers, may engage in transactions with us, or may perform services for us in the ordinary course of their businesses.

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To the extent required, this prospectus may be amended or supplemented from time to time to describe a particular plan of distribution. The place and time of delivery for the securities in respect of which this prospectus is delivered will be set forth in the accompanying prospectus supplement.

Each series of offered securities will be a new issue, and other than the shares of Transocean Ltd., which are listed on the NYSE, will have no established trading market. The issuers may elect to list any series of offered securities on an exchange, but the issuers are not obligated to do so. It is possible that one or more underwriters may make a market in a series of offered securities. However, they will not be obligated to do so and may discontinue market making at any time without notice. The issuers cannot assure you that a liquid trading market for any of our offered securities will develop.

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### VALIDITY OF THE SECURITIES
The validity of the securities offered hereby will be passed upon by Carey Olsen, Grand Cayman, Cayman Islands, as to matters of Cayman Islands law, by Baker Botts L.L.P., Houston, Texas, as to certain matters relating to U.S. law and by Homburger AG, Zurich, Switzerland as to matters of Swiss law. Any underwriters will be advised about matters relating to any offering by their own legal counsel.

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### 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, 2023 (including the schedule appearing therein), and the effectiveness of Transocean Ltd. and subsidiaries’ internal control over financial reporting as of December 31, 2023, 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.

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#### Transocean Ltd.

#### 125,000,000 Shares