Now that Warren Buffett has said Greg Abel will succeed him as Berkshire Hathaway’s CEO at year-end, Berkshire watchers are turning their attention to a different succession mystery: Who will fill Ajit Jain’s shoes? 

For nearly four decades, Jain has been the brains behind Berkshire’s insurance powerhouse. Its profits have helped Buffett expand his conglomerate and seed his stock portfolio. A risk-pricing mastermind, Jain has crafted policies insuring Chicago’s tallest building against terrorist attacks, Pepsi against having to award a $1 billion raffle prize, and baseball teams in the event that star players such as Alex Rodriguez got hurt. Along the way, he has made Berkshire billions of dollars.