Jon Corzine, one of Wall Street's best-known bankers, unexpectedly stepped down yesterday as co-chief executive of Goldman Sachs, the top global investment bank.

In a management reshuffle marking a significant power shift as Wall Street's leading investment banking partnership prepares to turn itself into a public company, Hank Paulson is to become sole chief executive and joint chairman with Mr Corzine.

The move shocked Goldman Sachs' competitors, coming just months before the firm's renewed attempt to float on the stock market.

Mr Paulson described the reshuffle as "an orderly transition", assuring the firm's partners, staff and investors that the "entire management team is lined up behind the initial public offering".

As part of the changes, John Thornton, who runs Goldmans' Asian operations, and John Thain, chief financial officer, are promoted to joint-chief operating officers. The move is seen as marking them out as future leaders of the firm and ensuring their support for the IPO.