Oct. 25 (Bloomberg) -- Merrill Lynch & Co., the largest brokerage firm, may have to write down another $4 billion in the fourth quarter as the value of subprime assets continues to drop, according to CIBC World Markets.

``Thus far, Merrill has taken the largest writedown of its financial peers, but unfortunately, we believe in aggregate it will only get larger,'' CIBC analyst Meredith Whitney said in a report released yesterday. She kept her recommendation at ``sector performer'' while cutting her fourth quarter earnings estimate to a 50-cent per share loss.

Goldman Sachs Group Inc. and UBS AG cut their ratings and share-price projections for New York-based Merrill Lynch after the securities firm posted the biggest loss in its 93-year history yesterday. It wrote down subprime mortgages and asset- backed bonds by $7.9 billion, posting a third-quarter loss of $2.24 billion, or $2.82 per share. It also wrote down the value of loans to finance leveraged buyouts by $463 million.

To contact the reporter on this story: Yalman Onaran in New York at yonaran@bloomberg.net.

Last Updated: October 25, 2007 09:18 EDT