JPMorgan's COO is leaving the bank

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

Dimon did not provide a reason for Zames's departure but thanked him for his 13 years with the bank and said he was sad to see him go.

"Matt has worked tirelessly across many disciplines to help make us a better company. We are extremely grateful for his efforts and appreciate his enormous contributions," Dimon wrote in the memo.

Zames, 46, was among several deputies considered a potential successor to Dimon.

He was named JPMorgan's chief investment officer in 2012 in the wake of the London Whale trading fiasco. Shortly after he was promoted to co-COO, and by 2013 he won the job outright.

Before joining JPMorgan in 2004, Zames worked as a managing director at Credit Suisse where he was the co-head of US Rated Trading. Prior to that, he was a trader at Long Term Capital Management INC - a hedge fund that failed in the late 1990s.

(Reporting by Dan Freed; Writing by Lauren Tara LaCapra and Jonathan Oatis)