Merrill Lynch & Co. reported the biggest quarterly loss in its 93-year history after $8.4 billion worth of writedowns.

The third-quarter loss of $2.24 billion, or $2.82 a share, was about six times higher than the New York-based company estimation on Oct. 5.

Merrill Lynch wrote down the value of subprime mortgages, asset-backed bonds and loans to finance leveraged buyouts.

Chief Executive Officer Stanley O’Neal said in a statement today that the company expects market conditions for subprime mortgage-related assets to continue to be uncertain and that it’s working to resolve the remaining impact.

Merrill Lynch fell sharply in trading this morning on the New York Stock Exchange.