With the global economic downturn deepening and confidence in the financial system still elusive, the International Monetary Fund estimates that banks and other financial institutions face aggregate losses of $4.1 trillion in the value of their holdings as a result of the crisis.

In its global financial stability report, released Tuesday, the fund estimated that financial institutions would have to write down an estimated $2.7 trillion in loans and securities originating in the United States from 2007 to 2010. That estimate is up from $2.2 trillion in the fund's report in January, and $1.4 trillion last October.