Note 1Business Transocean Ltd. (together with its subsidiaries and predecessors, unless the context requires otherwise, Transocean, we, us or our) is a leading international provider of offshore contract drilling services for oil and gas wells. We specialize in technically demanding sectors of the offshore drilling business with a particular focus on deepwater and harsh environment drilling services. Our mobile offshore drilling fleet is considered one of the most versatile fleets in the world. We contract our drilling rigs, related equipment and work crews predominantly on a dayrate basis to drill oil and gas wells. At September 30, 2017, we owned or had partial ownership interests in and operated 38 mobile offshore drilling units, including 25 ultra-deepwater floaters, seven harsh environment floaters, two deepwater floaters and four midwater floaters. At September 30, 2017, we also had four ultra-deepwater drillships under construction or under contract to be constructed. On August 13, 2017, we entered into a transaction agreement (the Transaction Agreement) with Songa Offshore SE, a European public company limited by shares, or societas Europaea, existing under the laws of Cyprus (Songa), pursuant to which we will offer to acquire all of the issued and outstanding shares of Songa, subject to certain conditions, through a public voluntary exchange offer (the Offer). At September 30, 2017, Songa owned and operated seven mobile offshore drilling units, including four harsh environment floaters and three midwater floaters. See Note 4Business Combination. On May 31, 2017, we completed the sale of 10 high-specification jackups and novated the contracts relating to the construction of five high-specification jackups, together with related assets. At September 30, 2017 we continued to operate two high-specification jackups that were under contract when we sold the rigs, and we will continue to operate such rigs until completion or novation of the respective drilling contracts. See Note 6Drilling Flee