CDO ratings blow for banks

Banks may be the latest victims of a continuing drive by rating agencies to impose harsher tests on highly rated structured finance products, analysts say.

After a tightening-up of ratings criteria at Fitch Ratings in April last year, Moody's and Standard & Poor's have since followed suit.

Since the outbreak of the US subprime mortgage crisis, rating agencies have been placed under intense pressure by regulators. In particular, they have homed in on the so-called "cliff risk" posed by structured f