The collapse of Lehman Brothers one year ago claimed another scalp last night, when Wall Street titan John Mack quit as the chief executive of Morgan Stanley.

An archetypal investment banker regarded as smooth and ruthless in equal measure, Mack is being replaced by a man whose background is in wealth management - a significant shift of emphasis.

James Gorman, a 51-year-old Australian, denies that Morgan will move away from capital markets and investment banking.

But analysts say his experience is indicative of a new atmosphere post-Lehman. Formerly head of private client business at Merrill Lynch, Gorman was the bank's co-president for global wealth management until yesterday.

Bill Fitzpatrick, an analyst for Optique Capital Management in the US, said: "All these financial institutions are going to replace their head honchos with someone with a background in a business with a more predictable, consistent revenue stream."

Mack will stay on as chairman. He could have kept the top job for longer, according to American reports, but indicated that steering the company through the Lehman Brothers debacle had left him shattered. Critics say he lost his nerve and reigned in traders at a time when arch-rival Goldman Sachs was willing to ramp up risk and chase trading profits with venom.

Mack's history with Morgan goes back decades. In 1997, he led the merger with credit card company Dean Witter, a huge deal at the time that sparked consolidation among the top banks, leading to the creation of today's "too big to fail" behemoths.

He was ousted after a power struggle with then chief executive Philip Purcell but returned in 2005. The top London Morgan executive is now Walid Chammah, who runs the investment banking arm and becomes chairman of Morgan Stanley International.

He is said to have ruled himself out of the very top job by declining to move from his South Kensington home.