Morgan Stanley (MS) on Wednesday promoted its investment banking chief, Colm Kelleher, to president, making him the heir apparent to current Chief Executive James Gorman, and prompting Greg Fleming, the head of wealth management, to depart.

Fleming, who was once seen as a likely successor to Gorman, before losing out in a management reshuffle in October, emailed the bank’s 15,800 brokers to tell them the new year would bring challenges “on the horizon beyond Morgan Stanley.”

Speaking at a Reuters event last June, Fleming said he hoped to reshape the bank’s wealth management’s workforce in the coming years to include more women and millennial advisers, and was investing more in the firm’s technology in order to attract them.

Fleming, who is seen by Wall Street power brokers as CEO material and ambitious to lead a major company, declined Morgan Stanley’s offer to stay on and told the firm this week he was leaving, a source said.

In addition to becoming president, Kelleher, 58, will take on Fleming’s responsibilities overseeing wealth management. His elevation to president makes him the second most powerful executive at Morgan Stanley and the obvious successor to Gorman, who is nearly six years into a turnaround plan.

But Gorman, 57, is in no hurry to leave, and because they are close in age, there is no guarantee that Kelleher will eventually replace him.

Other potential successors include Chief Financial Officer Jon Pruzan, head of trading Ted Pick and Shelley O’Connor, a veteran of the wealth management business who was promoted as co-head of the division on Wednesday along with Andy Saperstein.

“James Gorman’s going to be there a long time. I’m not really thinking about who’s going to succeed him when he leaves,” Sandler O’Neill analyst Jeff Harte said.

A trading veteran known for his sarcastic sense of humor, Kelleher was Morgan Stanley’s chief financial officer during the 2007-09 financial crisis and helped shrink the bank’s balance sheet from $1 trillion in 2007 to $659 billion in 2008.

“He achieved one of the most miraculous shrinkages of a company that I’ve ever seen ever,” Rafferty Capital Markets analyst Dick Bove said.

Kelleher is currently overseeing a retrenchment of Morgan Stanley’s fixed-income trading business, with 1,200 jobs set to be axed worldwide.

Morgan Stanley’s bond trading revenue slid 42% during the third quarter, in one of the bank’s worst performances since the financial crisis.

Shares of Morgan Stanley have fallen over 21% in the last 12 months, compared with a decrease of 12% from arch rival Goldman Sachs Group Inc.

Bove said Kelleher’s appointment was about creating a balance of power at Morgan Stanley between wealth management, where Gorman’s expertise lies, and the securities unit overseen by Kelleher.

“Why would you have two wealth management guys running the company? If you do that, you’re signaling to anyone who doesn’t work in wealth management that they have no future at Morgan Stanley,” he said.

It is the second time Kelleher, a 27-year veteran of the bank, has won out in internal power struggles.

In 2012, Paul Taubman, one of Morgan Stanley’s top dealmakers, left the bank after Kelleher was named as sole head of sales and trading, a division they had run jointly.

A native of county Cork in Ireland, Kelleher spent a large part of his youth in England and currently splits his time between London and New York.

Fleming, who joined Morgan Stanley in 2009, was widely seen as a successor to Gorman. He helped grow Morgan Stanley’s wealth management arm into an operation that generated nearly half of the firm’s revenue as it shifted away from trading to more stable earnings. Fleming also steered the bank through its merger with Citigroup’s (C) Smith Barney brokerage.

But his star appeared to fade in October when his responsibilities were narrowed to focusing solely on wealth management. The task of running the investment management unit, which he had led, was given to Dan Simkowitz, an investment banker who co-led the firm’s stock—and debt-underwriting business.

Fleming has been left at the altar before.

During the financial crisis, a period when Fleming was president and chief operating officer at Merrill Lynch, the board of Merrill Lynch made him interim chief executive, but his role was short-lived. It hired John Thain, a former Goldman Sachs Group Inc executive, to fill the job permanently.

After helping to negotiate the sale of Merrill Lynch to Bank of America (BAC) at the height of the crisis, Fleming left Wall Street and went to teach at Yale Law School, his alma mater.

Morgan Stanley lured him back to the banking world in 2010 and he gained clout after he steered Morgan Stanley Wealth Management through a complicated merger with Citigroup’s Smith Barney brokerage, lifting the division’s profit margins to a targeted level after a bumpy start.

“Greg Fleming is a strong manager who could run something bigger or become CEO somewhere,” said analyst Mike Mayo of securities firm CLSA. “He got the job done in executing the brokerage merger and we wouldn’t be surprised to see him running something bigger, or becoming CEO at another firm over time.”