Billionaire Warren Buffett will retire at the end of the year, bringing the curtain down on a six-decade run leading Berkshire Hathaway that made him the most influential investor in the world. Mr. Buffett said he will recommend to Berkshire Hathaway’s board on Sunday that Vice Chairman Greg Abel should replace him.

“I think the time has arrived where Greg should become the chief executive officer of the company at year end,” Mr. Buffett said.

Mr. Abel has been Mr. Buffett’s designated successor for years, and he already manages all of Berkshire’s noninsurance businesses. But it was always assumed that he would not take over until after Mr. Buffett’s death. Previously the 94-year-old Mr. Buffett always said he had no plans to retire.

Mr. Buffett announced the news at the end of a five-hour question and answer period without taking any questions about it. He said the only board members who knew this was coming were his two children, Howard and Susie Buffett. Mr. Abel, who was sitting next to Mr. Buffett on stage, had no warning.

Mr. Abel returned an hour later without Mr. Buffett to conduct the company’s formal business meeting, and he responded to the news.

“I just want to say I couldn’t be more humbled and honored to be part of Berkshire as we go forward,” Mr. Abel said.

Many investors have said they believe Mr. Abel will do a good job running Berkshire, but it remains to be seen how good he will be at investing Berkshire’s cash. Mr. Buffett endorsed him Saturday by pledging to keep his fortune invested in the company.

“I have no intention — zero — of selling one share of Berkshire Hathaway. I will give it away eventually,” Mr. Buffett said. “The decision to keep every share is an economic decision because I think the prospects of Berkshire will be better under Greg’s management than mine.”

Thousands of investors in the Omaha arena gave Mr. Buffett a prolonged standing ovation after his announcement in recognition of his 60 years leading the company.

During that period Berkshire nearly doubled the returns of the S&P 500, with a 19.9 percent compounded annual growth rate compared with the index’s 10.4 percent gain.

Mr. Buffett had such a devoted following among investors that markets would move when his investments were disclosed because so many people copied him.

CFRA research analyst Cathy Seifert said it had to be hard for Mr. Buffett to decide to step down.

“This was probably a very tough decision for him, but better to leave on your own terms,” Ms. Seifert said. “I think there will be an effort at maintaining a ‘business as usual’ environment at Berkshire. That is still to be determined.”

Abel in the Wings

In many respects, Mr. Abel has already been running much of the company for years. But he hasn’t been managing Berkshire’s insurance operations or deciding where to invest all of its cash. He will now take those tasks on, but Vice Chairman Ajit Jain will remain to help oversee the insurance companies.

Investment manager Omar Malik of Hosking Partners in London said before Mr. Buffett’s announcement that he wasn’t worried about Berkshire’s future under Mr. Abel.

“Not really (worried). He’s had such a long time alongside Warren and a chance to know the businesses,” Mr. Malik said about Mr. Abel. “The question is will he allocate capital as dynamically as Warren? And the answer is no. But I think he’ll do a fine job with the support of the others.”

Cole Smead of Smead Capital Management said he wasn’t surprised Mr. Buffett is stepping down after watching him Saturday because the 94-year-old wasn’t as sharp as in past years. At one point, he made a basic math mistake in one of his answers. At other points, he got off track while telling stories about Berkshire and his investing without answering the question he was asked.

Mr. Abel is well regarded by Berkshire’s managers and Mr. Buffett has praised his business acumen for years. But he will have a hard time matching Mr. Buffett’s legendary performance, and since he doesn’t control 30 percent of Berkshire’s stock like Mr. Buffett does, he won’t have as much leeway.

“I think the challenge he’s going to have is if anyone is going to give him Buffett or (former Vice Chairman Charlie) Munger’s pass card? Not a chance in God’s name,” Mr. Smead said. Mr. Buffett always enjoyed a devoted following among shareholders.

Mr. Buffett has said that Mr. Abel might even be a more hands-on manager than he is and get more out of Berkshire’s companies. Managers within the company say they have to be well prepared before talking to Mr. Abel because they know he will ask tough questions.

A Warning on Tariffs

Mr. Buffett earlier warned that President Trump’s tariffs were harmful

Earlier Saturday, Mr. Buffett warned of dire global consequences from Mr. Trump’s tariffs while telling the thousands of investors gathered at his annual meeting that “trade should not be a weapon” but “there’s no question that trade can be an act of war.”

Mr. Buffett said Mr. Trump’s trade policies have raised the risk of global instability by angering the rest of the world.

“It’s a big mistake in my view when you have 7.5 billion people who don’t like you very well, and you have 300 million who are crowing about how they have done,” Mr. Buffett said as he addressed the topic on everyone’s mind at the start of the Berkshire Hathaway shareholders meeting.

While Mr. Buffett said it is best for trade to be balanced between countries, he doesn’t think Mr. Trump is going about it the right way with his widespread tariffs. He said the world will be safer if more countries are prosperous.

Still Hoarding Cash

Mr. Buffett said he just doesn’t see many attractively priced investments that he understands these days, so Berkshire is sitting on $347.7 billion in cash, but he predicted that one day Berkshire will be “bombarded with opportunities that we will be glad we have the cash for.”

Mr. Buffett said the recent turmoil in the markets that generated headlines after Mr. Trump’s tariff announcement last month “is really nothing.” He dismissed the recent drop as relatively small. He cited when the Dow Jones industrial average went from 240 on the day he was born in 1930 down to 41 during the Great Depression as a truly significant drop in the markets. Currently the Dow Jones Industrial Average sits at 41,317.43.

“This has not been a dramatic bear market or anything of the sort,” he said.

Mr. Buffett said he hasn’t bought back any of Berkshire’s shares this year either because they don’t seem to be a bargain either.