The oil rig was owned by Transocean, but leased by BP.
"In September 2014, a U.S. District Court judge ruled that BP was primarily responsible for the oil spill because of its gross negligence and reckless conduct. In April 2016, BP agreed to pay $20.8 billion in fines, the largest corporate settlement in United States history."
"In September 2014, a U.S. District Court judge ruled that BP was primarily responsible for the oil spill because of its gross negligence and reckless conduct. In April 2016, BP agreed to pay $20.8 billion in fines, the largest corporate settlement in United States history."
[1] https://www.britannica.com/event/Deepwater-Horizon-oil-spill
[2] https://en.wikipedia.org/wiki/Deepwater_Horizon_oil_spill