Moody's Investors Service apparently decided that downgrading a wide swath of Alt-A backed RMBS deals on a bond market holiday would be good for kicks. The details (subscription req'd for links): All of the above are first-lien, Alt-A deals; each issuer is seeing at least some prior investment grade ratings turn into junk ratings with these downgrades. The rest of the downgrades are so far hitting mezzanine and equity tranches. I'd list all the classes, but there are simply too many to cover here. Moody's did not provide a dollar value in terms of the affected classes, but it would seem pretty clear that the mortgage crunch is extending in full swing to Alt-A deals. For more information, visit