NEW YORK (Bloomberg) — Standard & Poor's said the end is in sight for write-downs on debt linked to sub-prime mortgages by the world's financial institutions.

Write-downs from sub-prime-tied securities will probably rise to $285 billion, New York-based S&P said yesterday in a report. The ratings company previously estimated losses of $265 billion in January. S&P raised its estimate because of increased loss assumptions for collateralised debt obligations.

"The positive news is that, in our opinion, the global financial sector appears to have already disclosed the majority of valuation write-downs" on sub-prime debt, S&P credit analyst Scott Bugie said in a statement. Losses on other debt such as leveraged loans are still likely to increase, the report said.

The world's largest banks and securities firms, led by Citigroup Inc., UBS AG and Merrill Lynch & Co., have reported more than $188 billion of mortgage-related losses since the start of last year, according to data compiled by Bloomberg. Sub-prime write-downs are coming not only at banks but also hedge funds, insurers and institutional investors, S&P said.

S&P's report helped prompt a rally in US stocks and a decline in Treasuries.

S&P, Moody's Investors Service and Fitch Ratings have been criticised by lawmakers and regulators for failing to anticipate the record home foreclosures that led to a slump in securities linked to mortgages to people with poor credit. S&P assigned AAA ratings to about 85 percent of mortgage CDO classes created in 2005, 2006, and 2007.