“But at its core, look: I’ll be 47 in October,” he added. “I want to get back to running the railroad — running my railroad, running my business. So it’s just a natural point.”
His exit is sure to rekindle speculation about who will succeed Mr. Dimon, who at 61 is in his 11th year as chief executive of the large international bank and has shown little interest in leaving.
In the wake of the 2012 “London whale” trading loss of $6 billion, a series of executives left the bank, including James E. Staley, Micheal J. Cavanagh and Frank J. Bisignano, who at various points were seen as possible heirs apparent.
More recently, the focus has shifted to up-and-comers like Marianne Lake, the bank’s chief financial officer, as well as on established players like Gordon Smith, its chief executive of consumer and community banking, and Daniel Pinto, who runs the corporate and investment bank.
Shares of JPMorgan rose 1.24 percent on Thursday.
Mr. Zames, who had also been regarded as a potential candidate to be chief executive, said on Thursday that a feeling that he would not obtain that job was not a motivating factor in his decision to leave.
The executive has long been associated with crisis management. Mr. Zames worked as a junior trader at Long-Term Capital Management, the hedge fund that had to be rescued in 1998, before playing a leading role in JPMorgan’s emergency takeover of Bear Stearns in 2008.
He later recalled walking in to Bear’s Madison Avenue office tower late one evening in March 2008. Bear’s officers had realized that a series of client cash withdrawals had rendered their company insolvent, and Mr. Zames summed up the situation with some characteristically blue language, saying the “whole thing” was headed in a very bad direction. That office building, one of the most valuable assets sold to JPMorgan in its hasty purchase of Bear, was where Mr. Zames later worked.
He did his share of troubleshooting at JPMorgan, too. In the London whale episode, Mr. Zames helped unwind some exotic trades that had created billions of dollars in losses for the bank. He then took over the role of chief investment officer in 2012, reshaping the department that had made the risky transactions and marred JPMorgan’s reputation.
At the time, Mr. Dimon praised Mr. Zames as a “world-class risk manager.”
Mr. Zames, a father of three who kept a low public profile, is unvarnished in more private settings. He is known both on Wall Street and in Washington, where he was chairman of the Treasury Borrowing Advisory Committee, a panel of investors that counsels the agency on the economy and on technical government-debt issues. Shortly before leaving that panel last year, Mr. Zames wrote a letter to Jacob J. Lew, then the Treasury secretary, warning that future debt-limit fights in Congress could lead to “another catastrophic financial crisis.”
Mr. Zames counted some of the most senior hedge fund managers as both clients and personal friends, and was known for giving tough advice, even to competitors.
Kenneth C. Griffin, founder of the Chicago money-management firm Citadel, said that he had been impressed with Mr. Zames since meeting him as a student at M.I.T., 25 years ago.
“Matt’s profound impact on JPMorgan reflects the combination of brilliance I saw in him then,” Mr. Griffin said in an email.
His happiest years at JPMorgan were probably spent running its multi-thousand-person fixed-income business, walking the trading floors of the former Bear building. There he studied markets ranging from interest rates to currencies and mortgage bonds, looking for moments when traders seemed to be reaching consensus on the market’s direction. At those times, he believed, prices were often on the verge of turning unexpectedly.
He often called his bond shop the “Walmart” of trading because of its heavy and lucrative flow of buy and sell orders from clients around the world. At one point, he set up a trading floor office for the head of the investment bank at the time, Mr. Staley, now chief executive of Barclays of Britain, to give him more direct exposure to the market’s dynamics.
“My philosophy has always been if you can create a flood of volume through your pipes, you’re meaningfully reducing your risk,” Mr. Zames said on Thursday. “And your business will trade at a higher multiple if you do it.”
Under terms of an agreement with JPMorgan filed Thursday, Mr. Zames can collect more than $10 million in compensation in the coming two years if he avoids joining a competing company until February of 2018, among other requirements.
Because of an editing error, an earlier version of this article misspelled the given name of a former executive at JP Morgan Chase. He is Michael J. Cavanagh, not Micheal.