Refer to the input text as context and select the correct relationship between 'Berkshire Hathaway' and 'Warren Buffett' from the available options.
Options: employer, operator, owned by, chief executive officer

(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