SCHEDULE 13D/A

Transocean Ltd.

Shares, $0.10 par value · CUSIP: H8817H100

Event date: 2025-09-30

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Frederik W. MohnReported CIK 0001729638

  Shares: 95,418,301.00 · Class: 10.1%

• Perestroika ASReported CIK 0001729635

  Shares: 95,074,894.00 · Class: 10.1%

• Perestroika (Cyprus) LtdReported CIK 0001737912

  Shares: 95,074,894.00 · Class: 10.1%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.