JPMorgan CEO Jamie Dimon recovering after emergency heart surgery

New York(CNN Business) JPMorgan Chase chief executive Jamie Dimon is recovering after undergoing emergency heart surgery, the company's co-COOs Gordon Smith and Daniel Pinto said in a letter to employees, shareholders and clients Thursday evening.

The board has directed Smith and Pinto to take over leading the company while Dimon recovers. JPMorgan (JPM) shares fell more than 1% in after hours trading following the news.

Dimon, 63, experienced an "acute aortic dissection" — a tear in the inner lining of the aorta blood vessel — requiring surgery Thursday morning.

"The good news is that it was caught early and the surgery was successful," Pinto and Smith said in the letter. "He is awake, alert and recovering well."

Dimon is one the most powerful men on Wall Street. He has been CEO of JPMorgan since 2005, and chairman of the board since 2006.

"Jamie Dimon is the literal JPMorgan of the modern world," Jeffrey Sonnenfeld, management professor at Yale University, told CNN Business. "There is no more feared or revered person today in the world of finance than Jamie Dimon."

Dimon has successfully built up a strong bench of talent behind him at JPMorgan, although over the years many of those lieutenants have left the bank to take senior roles elsewhere. Barclays (BCLYF) CEO Jes Staley, Wells Fargo (WFC) CEO Charlie Scharf and Fiserv (FISV) President and COO Frank Bisignano all used to work under Dimon at JPMorgan.

In their letter, Smith and Pinto, who are also co-presidents at JPMorgan, said they have worked "hand-in-hand" with Dimon to lead the company over the past two years.

"We have also been deeply involved in all of the critical firmwide functions," they said.

Smith also works as CEO of Consumer and Community Banking, managing a team of 135,000 employees, according to the company's website. He started at Chase in 2007.

Pinto is also CEO of the company's Corporate and Investment Bank. He began his career at JPMorgan Chase's predecessor companies in the 1980s.

"He has built up an incredible bench strength beneath him continually," Sonnenfeld said. "Gordon Smith has the Jamie Dimon gift of clarity and wit. They are in fantastic hands in terms of next generational cohort."

Dimon's health has been a concern in the past.

Dimon underwent treatment for throat cancer in 2014. He recently spoke with CNN about living more "deliberately" after his fight with cancer.

"Everyone knows they're going to die, but at one point it's right here and you realize it's true and it's true maybe sooner than you think," Dimon said. "And so it's nice to end every day by saying, 'That was a good day.' Every meeting, that was a good meeting. Every week, that was a good week."

The health scare also comes at a delicate time for JPMorgan and Wall Street.

Financial markets have been rocked in recent weeks by recession fears triggered by the coronavirus outbreak. Banks, including JPMorgan, have seen their stock prices fall sharply because of economic concerns and record low bond yields.

Many companies are testing contingency plans in case the health crisis worsens. JPMorgan recently asked thousands of employees to work from home for a day to test their remote access capabilities, a person familiar with the matter told CNN Business.