BP has accepted a $4 billion payment from Anadarko Petroleum, a former partner firm, in settlement over claims related to last year’s devastating oil spill in the Gulf of Mexico. Anadarko held a 25 percent stake in the Macondo well when the Deepwater Horizon oil rig exploded, and the company filed gross-negligence claims against BP after the disaster. But BP said it was not solely responsible for the rig explosion, and Monday's settlement adds support to that claim. Anadarko would have been able to avoid paying anything if BP was found to be grossly negligent; on the other hand, if BP was acquitted, then Anadarko would have been liable for 25 percent of a bill totaling $42 billion, which would have amounted to around $10 billion. Anadarko has dropped the negligence suit.