Two new contenders to replace Citigroup's chief executive Charles Prince emerged today when America's largest bank on Monday promoted Michael Klein and Tom Maheras to co-chairmen and chief executives of its markets and banking unit.

Mr Klein and Mr Maheras replace Robert Druskin, who was named in December as Citigroup’s chief operating officer. They had previously been co-presidents of the markets and banking unit.

There had been speculation that Mr Klein was about to leave Citigroup, whose shares have been hit by concerns over the performance of both the group and Mr Prince.

Earlier this month 4 per cent-shareholder Prince Alwaleed bin Talal of Saudi Arabia urged Mr Prince to take "draconian" measures in the face of a sluggish share price and criticisms that the bank was unwieldy.

Both Mr Kelin will continue to have primary oversight of global banking, including the investment bank, while Maheras will continue to oversee capital markets, including trading.

Mr Prince said: “Citi Markets & Banking is key to our growth plans and I am confident that Michael and Tom will take this business to even greater heights.”

Citigroup last month agreed to buy the hedge fund Old Lane and install it’s co-founder, Vikram Pandit, as chief of its alternative investments unit.

A month earlier, it hired American Express's chief financial officer Gary Crittenden to the same role at Citigroup.