Company: RIG
Filing Date: 2025-09-24
Form Type: 424B5
Source: 0001451505-25-000097
Chunk: 42

Company: Transocean Ltd.
Filing Date: 2025-09-24
Form: 424B5
Chunk 42
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 Tax Administration, which in turn provides the information to the U.S. tax authorities. The U.S and Switzerland agreed to change from the existing Model 2 IGA to the FATCA Model 1 IGA. The envisaged timeline for the implementation is January 2027, subject to the approval of the Swiss Parliament. The negotiations were concluded on November 13, 2023, and on June 27, 2024, the Swiss Federal Tax Administration issued a press release announcing the signing of a reciprocal FATCA Model 1 intergovernmental agreement (the**

<div align='center'>S-25</div>

“Model 1 IGA”). This means that Switzerland will also receive account data from the United States in the future. Swiss financial institutions will no longer provide the required data to the U.S. authorities, but rather to the Swiss Federal Tax Administration, which will then transmit it to the Internal Revenue Service. In Switzerland, the implementation of the Model 1 IGA necessitates changes to national law, which will be decided by the Federal Assembly. Such changes to national law implementing the Model 1 IGA are currently expected to enter into force in Switzerland on January 1, 2027. However, it is not possible to predict whether and when such changes will be enacted.

<div align='center'>S-26</div>

UNDERWRITING (CONFLICTS OF INTEREST) Under the terms and subject to the conditions in an underwriting agreement between us and the underwriters named below, for whom Citigroup Global Markets Inc. and Morgan Stanley & Co. LLC are acting as representatives, the underwriters have severally agreed to purchase, and we have agreed to sell to them, severally, the number of shares indicated below:

| Underwriter                   | Number of Shares |
| Citigroup Global Markets Inc. |                  |
| Morgan Stanley & Co. LLC      |                  |
| Total                         |                  |

The underwriters and the representatives are collectively referred to as the “underwriters” and the “representatives,” respectively. The underwriters are offering the shares subject to their receipt and acceptance of the shares from us and subject to prior sale, and the underwriters’ right to reject any order in whole or in part. The underwriting agreement provides that the obligations of the several underwriters to pay for and accept delivery of the shares offered by this prospectus supplement are subject to the approval of certain legal matters by their counsel and to certain other conditions. The underwriters are obligated to take and pay for