Utilize the input text as a context reference, choose the right relationship between Phillips 66 and Berkshire Hathaway from the options. Options: 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.

Phillips 66 was up 2.6 percent after Warren Buffett's Berkshire Hathaway disclosed a $4.48 billion stake in the oil refiner.

Answer: owned_by