・BP Exploration and Production Inc.* 65%
・Anadarko E&P Company LP 22.5%
・Anadarko Petroleum Corporation 2.5%
・MOEX Offshore 2007 LLC 10%
Here is a link from SubSeaIQ that states substantially similar ownership interests of the Deepwater Horizon | Macondo | Mississippi 252 oil prospect:
The Macondo prospect is located on Mississippi Canyon Block 252 in the Gulf of Mexico in a water depth of 4,993 feet (1,522 meters). BP serves as the operator, holding a 65% interest in the prospect; Anadarko holds 25%; and MOEX 2007 holds the remaining 10%.