NEW YORK (Reuters) - Morgan Stanley President Colm Kelleher, who has worked for the firm for roughly 30 years, will retire at the end of June, the bank said on Thursday.

FILE PHOTO: A sign is displayed on the Morgan Stanley building in New York U.S., July 16, 2018. REUTERS/Lucas Jackson

Kelleher, 61, will stay on as senior adviser, according to a memo Chief Executive James Gorman sent to employees that was seen by Reuters. Kelleher’s replacement was not immediately named.

Kelleher was president of the firm since January 2016, and widely known to be Gorman’s second-in-command.

KBW analyst Brian Kleinhanzl said Kelleher was thought of as a possible successor to the CEO if Gorman ever needed to step down suddenly.

Kelleher is older than Gorman, 60, and so was not thought of as a permanent successor, but his departure “raises some succession concerns near term” for the bank, Kleinhanzl said.

Kelleher served as chief financial officer and co-head of corporate strategy from October 2007 to December 2009. Gorman credited Kelleher’s leadership during that “critical period” with “helping the firm navigate the depths of the financial crisis,” according to the memo.

While Kelleher was CFO, the bank drastically shrank its balance sheet, became a bank holding company, which meant it could access funding from the Federal Reserve, and secured a $9 billion investment from Japanese bank Mitsubishi UFJ Financial Group.

Kelleher went on to become co-president and then president of institutional securities, as well as the head of international for the bank.

“Every time I have faced an issue of real significance Colm has been the most important person I have sought advice from,” Gorman wrote in the memo.

Kelleher joined the bank in 1989, initially working in the fixed income division. Reuters previously reported that Kelleher, a wine and classical music aficionado, was known by colleagues to care so deeply about the bank’s traditions that he chastised employees if they rolled up their shirt-sleeves because it lowered the standards of the business dress code.