(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.
In the context of the input sentence, determine the relationship between 'Phillips 66' and 'Berkshire Hathaway'.
Options: director/manager, member of, distribution format, owned by