Joseph Perella and Terry Meguid, two of Wall Street's top investment bankers, are understood to have resigned from Morgan Stanley. They are the latest senior-level departures sparked by a power struggle gripping the US bank.

Perella, a legendary deal-maker who was chairman of the institutional securities business, has been with the bank for more than 10 years. Meguid joined in 1978 and is now head of world-wide investment banking.