JPMorgan Chase & Co. Chief Operating Officer Matt Zames will leave the bank in the coming weeks, and his duties are being transferred to a number of other senior executives, Chief Executive Officer Jamie Dimon said in an internal memo seen by Reuters on Thursday.

Dimon did not provide a reason for Zames' departure but thanked him for his 13 years with the bank. Zames was among several deputies considered a potential successor to Dimon.

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

During his time at JPMorgan, Zames has 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, transformed its chief investment office and treasury arm after the so-called "London Whale" scandal in 2012 and has more recently been focused on critical technology and cyber functions.

In the memo, whose contents were confirmed by a spokesman, Dimon detailed a new organizational structure in which 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 will take on new responsibilities.