Underlying the festivities at Warren Buffett’s annual bash for Berkshire Hathaway Inc. shareholders over the weekend was a sobering fact: Finding the next big thing is hard.

The Berkshire chief executive officer spoke at length Saturday about his failure to pounce on opportunities in tech stocks, the challenge of lining up large deals, and his frustration with a cash pile that’s approaching $100 billion.

“We shouldn’t use your money that way for long periods,” Buffett said of the cash during his meeting in Omaha, Nebraska. “The question is, ‘Are we going to be able to deploy it?’ I would say that history is on our side, but it’d be more fun if the phone would ring.”

It was a notably downbeat moment for the billionaire, who’s spent the past five decades snapping up businesses and stocks. His investments transformed Berkshire from a struggling textile maker into a conglomerate with insurance