Transocean

Transocean was formed as a result of the merger of Southern Natural Gas Company, later Sonat, with many smaller drilling companies.

In 1953, the Birmingham, Alabama-based Southern Natural Gas Company created The Offshore Company after acquiring the joint drilling operation DeLong-McDermott from DeLong Engineering and J. Ray McDermott. In 1954, the company launched Rig 51, the first mobile jackup rig, in the Gulf of Mexico. In 1967, the Offshore Company went public. In 1978, SNG turned it into a wholly owned subsidiary. In 1982, it was changed to Sonat Offshore Drilling Inc., reflecting a change in its parent's name. William C. O'Malley, an executive at Sonat's headquarters in Birmingham, was named the company's first Chief Executive Officer in 1992. In 1993, Sonat spun off the majority of its ownership in the company. Sonat sold its remaining 40% stake in the company during a secondary public offering in late 1995.

In 1996, the company acquired Norwegian group Transocean ASA for US$1.5 billion. Transocean started in the 1970s as a whaling company and expanded through a series of mergers. The new company was called Transocean Offshore. The new company began building massive drilling operations with drills capable of going to 10,000 feet and operating two drill operations on the same ship. Its first ship, Discoverer Enterprise, cost nearly US$430 million and was 834 ft . The Enterprise class drillship is the largest of the drilling ships.In 1999, Transocean merged with Sedco Forex, the offshore drilling subsidiary of Schlumberger in a $3.2 billion stock transaction in which Schlumberger shareholders received shares of Transocean.Sedco Forex had been formed from a merger of two drilling companies, the Southeastern Drilling Company , founded in 1947 by Bill Clements and acquired by Schlumberger in 1985 for $1 billion and French drilling company Forages et Exploitations Pétrolières founded in 1942 in German-occupied France for drilling in North Africa. Schlumberger first got a foothold in the company in 1959 and then assumed total control in 1964, and renamed it Forex Neptune Drilling Company.In 2000, Transocean acquired R&B Falcon Corporation, owner of 115 drilling rigs, in a deal valued at $17.7 billion. With the acquisition, Transocean gained control of what at the time was the world's largest offshore operation. Among R&B Falcon's assets was the Deepwater Horizon. R&B Falcon had acquired Cliffs Drilling Company in 1998.In 2005, the company's Discoverer Spirit rig set a world record for the deepest offshore oil and gas well of 34,189 ft .In 2007, the US Department of Justice and the Securities and Exchange Commission filed a case against Transocean, alleging violations of the Foreign Corrupt Practices Act. The case alleged that Transocean paid bribes through its freight forwarding agents to Nigerian customs officials. Transocean later admitted to approving the bribes and agreed to pay US$13,440,000 to settle the matter.In 2007, the company merged with GlobalSantaFe Corporation in a transaction that created a company with an enterprise value of $53 billion. Shareholders of GlobalSantaFe Corporation received $15 billion of cash as well as stock in the new company for their shares. Robert E. Rose, who was non-executive chairman of GlobalSantaFe, was made Transocean's chairman. Rose had been chairman of Global Marine prior to its 2001 merger with Santa Fe International Corporation.In 2008, the company moved its headquarters to Switzerland, resulting in a significantly lower tax rate.In September 2009, its Deepwater Horizon rig established a 35,050 ft well, the deepest well in history – more than 5,000 feet deeper than its stated design specification.In 2010, Transocean was implicated in the Deepwater Horizon oil spill resulting from the explosion of one of its oil rigs in the Gulf of Mexico that was leased to BP.In 2011, the company acquired Aker Drilling, which owned 4 harsh environment rigs used for drilling near Norway.In 2012, the company sold 38 shallow water rigs and narrowed its focus on high-specification deepwater rigs.In 2013, the company was added to the S&P 500 index.In February 2015, CEO Steven Newman quit following a $2.2 billion quarterly loss.Effective on 30 March 2016, the company delisted its shares from the SIX Swiss Exchange, at which time its shares were removed from the Swiss Market Index.Effective on January 30, 2018, the company completed its acquisition of Songa Offshore.In December 2018, the company acquired Ocean Rig.