NEW YORK (Reuters) - JPMorgan Chase & Co JPM.N Chief Operating Officer Matt Zames, once seen as a likely successor to Chief Executive Jamie Dimon, will leave the bank in the coming weeks, and his duties are being split among other senior executives, the bank said on Thursday.

A view of the exterior of the JP Morgan Chase & Co. corporate headquarters in New York City May 20, 2015. REUTERS/Mike Segar/Files

In an internal memo announcing Zames’ departure, Dimon thanked him for his 13 years of service but did not say why he was going.

A person familiar with the matter said Zames, who did not return a call seeking comment, wanted to run a company on his own and saw JPMorgan’s upper management ranks as too crowded.

The exit stirs up, once again, one of Wall Street’s favorite parlor games - trying to work out who will succeed Dimon, 61, at the helm of the largest U.S. bank.

At 46, Zames was the youngest of the six contenders and had the advantage of knowing all segments of the bank, after overseeing areas including cyber security, technology and real estate.

Zames also played a central role in keeping the bank stable amid financial turmoil. He helped stabilize Bear Stearns, after JPMorgan acquired the investment bank during the 2007-2009 crisis, and transformed JPMorgan’s chief investment office and treasury arm after the so-called “London Whale” scandal in 2012. More recently, he was focused on critical technology and cyber functions.

“While I am sad to see him leave, I respect his decision and all he has done for JPMorgan Chase,” said Dimon.

In the memo, Dimon detailed a new organizational structure in which the five other potential successors - Chief Financial Officer Marianne Lake, Corporate and Investment Bank CEO Daniel Pinto, Consumer and Community Banking CEO Gordon Smith, Asset Management CEO Mary Erdoes and Commercial Bank CEO Doug Petno - divvy up Zames’ responsibilities.

With Dimon showing no inclination to relinquish his role, a raft of potential successors has left the bank in recent years. Many have gone on to lead other institutions, including Barclays PLC BARC.L CEO Jes Staley, Standard Chartered PLC STAN.L CEO Bill Winters and former Visa Inc V.N CEO Charles Scharf.

Michael Mattioli, portfolio manager at Manulife Asset Management, which owns about 6 million JPMorgan shares, said the bank still has lots of highly capable leaders.

“They’ve built up such a high quality bench that a lot of these senior executives are going to be attractive to other companies,” he said.

Zames will receive discretionary payments of $4.625 million on Feb. 1, 2018 and $4.5 million a year later. He has agreed not to compete with JPMorgan until Feb. 1, 2018, not to solicit clients for a year after that date and not to hire employees of the bank before Feb. 1, 2020.

“Jamie has been a true mentor to me, and it has been a privilege to be a member of his team. I’m confident I will continue to benefit from his guidance and wisdom in the future,” Zames said in the memo.