We asked 6 big-money investors about their biggest fears — and they all had the same answer

What keeps you up at night? It's a question you'd expect to draw a wide range of responses when posed to investors responsible for tens of billions of dollars. After all, it's not exactly as if there's a shortage of anxiety-inspiring headlines floating around each day. But as Business Insider found out through a series of interviews, there's one worry to rule them all: the Federal Reserve's reversal of the unprecedented monetary stimulus that helped drag the US out of the latest...