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EXHIBIT 99.1 PTransocean TRANSOCEAN LTD . REPORTS FIRST QUARTER 2021 RESULTS • Total contract drilling revenues were $ 653 million ( total adjusted contract drilling revenues of $ 709 million ) , compared with $ 690 million in the fourth quarter of 2020 ( total adjusted contract drilling revenues of $ 747 million ) ; • Revenue efficiency ( 1 ) was 97.4 % , compared with 97.2 % in the prior quarter ; • Operating and maintenance expense was $ 435 million , compared with $ 465 million in the prior period ; • Net loss attributable to controlling interest was $ 99 million , $ 0.16 per diluted share , compared with net loss attributable to controlling interest of $ 37 million , $ 0.06 per diluted share , in the fourth quarter of 2020 ; • Adjusted EBITDA was $ 245 million , compared with adjusted EBITDA of $ 210 million in the prior quarter ; and . Contract backlog was $ 7.4 billion as of the April 2021 Fleet Status Report . STEINHAUSEN , Switzerland — May 3 , 2021 — Transocean Ltd. ( NYSE : RIG ) today reported a net loss attributable to controlling interest of $ 99 million , $ 0.16 per diluted share , for the three months ended March 31 , 2021 . First quarter 2021 results included net favorable items of $ 18 million , or $ 0.03 per diluted share , as follows : • $ 51 million , $ 0.08 per diluted share , gain on retirement of debt ; and • $ 27 million , $ 0.05 per diluted share , discrete tax items . These favorable items were partially offset by : • $ 60 million , $ 0.10 per diluted share , loss on disposal of assets . After consideration of these net favorable items , first quarter 2021 adjusted net loss was $ 117 million , $ 0.19 per diluted share .