In the context of the input sentence, determine the relationship between 'Berkshire Hathaway' and 'Warren Buffett'.
Options: platform, position held, headquarters location, chief executive officer

For example, two notable value investors operate businesses that fall into this category -- Tom Gayner at Markel and Warren Buffett at Berkshire Hathaway ( NYSE:BRK-A ) ( NYSE:BRK-B ) .
chief executive officer