Utilize the input text as a context reference, choose the right relationship between 'Berkshire Hathaway' and 'Warren Buffett' from the options.
Options: owned by, chief executive officer, employer, operator

(AP) -- Warren Buffett is making the biggest bet of his long investment career, a $32.36 billion buyout of Precision Castparts in a deal that will continue to reshape his Berkshire Hathaway conglomerate.
chief executive officer