The executives who led Bear Stearns Cos. before the big Wall Street firm's implosion two years ago say they did all they could to keep it afloat and nothing could have saved it once it fell victim to a run on the bank.

James Cayne, who was Bear Stearns' CEO until January 2008, and Alan Schwartz, who succeeded him for a few months, were testifying Wednesday before a special panel investigating the roots of the financial crisis.

Cayne says the firm's downfall was due to "overwhelming market forces."

Bear Stearns collapsed in March 2008 and the Federal Reserve orchestrated its buyout by JPMorgan Chase & Co. with a $29 billion federal backstop.