Principal at Barrow Hanley Mewhinney & Strauss
Estimated losses: $991.7 million*
The 29 year-old investment firm loaded up on Bear Stearn stock in 2007 and began the year owning nearly 10 percent of the firm.
*Estimates based on Barrow Hanley's holdings at the beginning of 2008, when the stock was trading at $88.35. NEXT: James "Jimmy" Cayne