Warren Buffett said Berkshire Hathaway Inc.’s investment in Delta Air Lines Inc. rose above his comfort threshold by mistake.

The stake climbed when Delta bought back its own stock and Berkshire increased its holdings, according to regulatory filings this month.

“What I didn’t realize was that that purchase had taken us over 10 percent,” Buffett said Thursday in a wide-ranging interview with CNBC. “I was already in territory I didn’t plan to get, so I just decided to buy a whole lot more stock.”

Atlanta-based Delta is the dominant carrier at Minneapolis-St. Paul International Airport and employs about 10,000 people in Minnesota.

Buffett spurned the airline industry for years after what he acknowledged was a bad bet on US Airways Group Inc. in 1989. But he’s been piling into airline stocks since 2016, buying up stakes in Delta, Southwest Airlines Co., American Airlines Group Inc. and United Continental Holdings Inc.

Buffett has been on the hunt for an “elephant-sized acquisition” to spend some of his more than $100 billion cash pile. Those ambitions had been hindered by “sky-high” prices for many businesses, the Berkshire CEO said in an annual letter released in February. He’d previously said he wouldn’t rule out owning an entire airline, and his recent wagers in the industry fueled speculation he had an appetite for such a deal.

“The airline industry is a very, very competitive business,” Buffett said Thursday. “I don’t think it’s a suicidal business anymore, but it was for quite a while.”

Here are some of Buffett’s comments on other topics:

On Boeing

Buffett said that Boeing Co. has a lot of work to do quickly following two fatal crashes that grounded its 737 Max airplanes. Still, he noted the overall increase industrywide in safety in recent years.

“The airline industry has been so safe,” Buffett said. “It’s almost impossible to believe how much that’s improved in terms of safety during my lifetime.”

On Lyft’s IPO

Buffett said he’s never been a big buyer of initial public offerings.

“Buying new offerings during hot periods in the market, I don’t think it’s anything the average person should think about at all,” he said.

On Apple

Apple Inc., among Berkshire’s largest investments, this week unveiled new digital services and a credit card with Goldman Sachs Group Inc. The technology company has room to take risks that may not work, Buffett said, adding that he isn’t predicting how these ventures will pan out.

“That’s a company that can afford a mistake or two,” Buffett said. “Apple should do some things that don’t work.”

Buffett brushed off any potential concerns about Apple entering the credit-card market, given that Berkshire also owns a stake in American Express Co. He said he likes his AmEx position and his Apple position as well.

On the Economy

The billionaire investor said that the U.S. economy appeared to be slowing its rate of increase, echoing comments he made after the release of his annual letter in February.

“It does look like the pace of increase in the economy has slowed down,” Buffett said. “I’d call it somewhere close to noticeably, but I wouldn’t go beyond that.”

On a Real Estate Lawsuit

Berkshire’s real estate brokerage network and some of its rivals are facing scrutiny in a lawsuit that alleges the companies have conspired to inflate commissions. Buffett said he doesn’t believe those groups work as a cartel and said the broker who sold his Emerald Bay vacation house spent his own funds to get the house sold without any assurance of a deal.

“If you’re looking for demons in the American capitalist system, I don’t think you’ll find it with your local real estate broker,” Buffett said.