Shares of Citigroup (NYSE:C) fell more than 4 percent in early trading on Monday, after news that the company could increase its write-downs by up to $11 billion more, following the departure of its CEO Charles prince.

Former Treasury Secretary Robert Rubin will take over for Prince as Citi's chairman. Sir Win Bischoff takes Prince's other role as acting CEO.

The company said that the write-down will be between $8 billion and $11 billion before taxes and could increase if the markets fro subprime mortgages worsens.

Citigroup fell $1.63, or 4.32 percent to $6.10 in early trading on the New York Stock Exchange.