Warren Buffett recently said he will turn over the job of Berkshire Hathaway CEO to Greg Abel at the end of the year. Berkshire Hathaway has built up a record pile of cash in recent quarters -- and Buffett still has time to put some of it to work if he finds the right opportunity.

Other fund managers also hold major stakes in Berkshire Hathaway Class B shares. BlackRock owns nearly 111.6 million Class B shares, roughly 8.3% of the total outstanding shares. State Street Corporation ranks high on the list as well, with nearly 71.7 million Class B shares making up 5.35% of the total.