Standard & Poor's Corp. boosted its projections for losses from alternative-A mortgages backing securities.

Losses on loans backing 2006 securities will reach an average of about 22.5% of the original balances, while losses for similar 2007 bonds will total about 27%, the rating agency said Monday.

The firm did not provide its previous forecasts.

Alt-A home loans were made to borrowers who wanted atypical terms such as proof-of-income waivers, delayed principal repayment or investment-property collateral, without having to offer sufficient compensating attributes.

S&P and other rating agencies have cut about 92% of the $593 billion of alt-A mortgage securities outstanding, excluding bonds backed by "option" adjustable-rate mortgages, according to a July 10 report from JPMorgan Chase & Co.

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