Transocean Ltd.
A contractor that runs a fleet of ultra-deepwater drillships and harsh-environment semisubmersibles, renting them out by the day to oil and gas companies worldwide. Its biggest vessels, like the Deepwater Atlas and Deepwater Titan, drill in waters too deep for fixed platforms, and it has agreed to acquire rival Valaris. The name traces to a 1926 rig-hand named "Stoney" Stoneman, who bought his first drilling rig with a personal check; his company later merged into today's Transocean.
Estimated from filings — the split-adjusted price range over the quarters each manager built the position. A range, not a fill price; 13F reports a quarter-end snapshot, not a trade date.