California’s attorney general said his office is investigating Wall Street’s big credit rating agencies to determine what role they may have played in the collapse of the financial markets.

Attorney General Jerry Brown said he has issued subpoenas to Moody’s Investors Service, Standard & Poor’s and Fitch Ratings to determine whether they violated state law in “recklessly giving stellar ratingsto shaky assets.”

At the peak of the housing boom, the agenciesgave their highest ratings to securities backed bysubprime mortgages that later fell apart.