Refer to the input text as context and select the correct relationship between 'Berkshire Hathaway' and 'Warren Buffett' from the available options.
Options: position held, chief executive officer, headquarters location, platform

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