Citigroup chief executive Vikram Pandit announced Tuesday that the bank would cut 4,500 jobs as it tries to cut costs in the face of tougher market conditions. \"We have started a firm-wide reduction of headcount this quarter that will affect roughly 4,500 positions and will be completed over the next few quarters,\" Pandit told a industry conference. But the layoffs will come at a stiff price for the company. \"We anticipate recording a charge in the fourth quarter for severance and other expenses related to this of approximately $400 million,\" he said. While income for the bank leapt in the third quarter, that was largely thanks to a one-off change in credit costs. Revenue was basically flat, amid what Pandit called \"a challenging economic environment.\"