Morgan Stanley's 5000 bankers at its Canary Wharf headquarters have started playing the guessing game over who will take over from veteran chief executive John Mack at the firm.

It is early days, with Mack, 64, expected to retire in 2010.

Possible successors include co-presidents Walid Chammah and James Gorman.

Whoever takes the job will have to steer the bank through a very different landscape. Morgan, like Goldman Sachs, has converted into a bank-holding company to secure a government cash infusion.

Chammah is a 15-year veteran of Morgan's core financing and investment-banking while Gorman previously ran Morgan's retail-brokerage unit.

Observers say the appointment of Chammah would suggest a focus on core institutional securities business while Gorman's aim could be to make Morgan more like a traditional bank.

Chief financial officer Colm Kelleher and investment banking chief Paul Taubman are outside chances, but some say it is too early to tell what the board is thinking.

“We'll know more in three or four months,” one insider said.