(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.
Refer to the input text as context and select the correct relationship between 'Phillips 66' and 'Berkshire Hathaway' from the available options.
Options: director/manager, owned by, member of, distribution format