There is a subtle undercurrent of fear on Wall Street about Alt-A loans. JPMorgan has about $19.5 billion worth of exposure to Alt-A mortgages, and it likely is not alone. I would be surprised if banks have written off much against these assets. CalculatedRISK notes that "subprime delinquencies appear to have peaked in December of 2007, and subprime foreclosure starts may have peaked in January of 2008," according to research firm Clayton. "Unfortunately, Alt-A seems nowhere near its peak yet." Delinquencies and foreclosures seem to be on an upsloping curve. This may be the start of another wave of writedowns.

For more: 
- here's the  CalculatedRISK item

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