Jerry Brown, state attorney general and Newsom gubernatorial rival, is in San Francisco this morning to announce a major financial investigation.

At a 10:30 a.m. press conference, Brown is expected to announce the launch of a probe into the role the credit rating agencies played in fueling the financial crisis.  Brown says that at the peak of the housing boom, the agencies gave their highest credit ratings to complicated financial instruments, including securities backed by subprime mortgages, so they would appear as safe as Treasury bonds issued by the government.

In rating the securities, agencies earned billions of dollars in revenue at a rate double what they earned for rating other financial products, all while working behind the scenes with Wall Street firms that created the securities backed by subprime mortgages.