What is the relationship between Phillips 66 and Berkshire Hathaway in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

(Reuters) - Warren Buffett's Berkshire Hathaway Inc (BRKa.N) disclosed a $4.48 billion stake in oil refiner Phillips 66 (PSX.N), rebuilding a bet it had made in the energy industry before oil prices fell.

Answer: owned_by