Bloomberg reported that McGraw-Hill and its Standard & Poor’s unit were sued by the U.S. over claims S&P knowingly understated the credit risks of bonds and derivatives that were central to the worst financial crisis since the Great Depression.

Bloomberg said the U.S. Justice Department filed a complaint accusing McGraw-Hill and S&P of three types of fraud, the first federal case against a ratings company for grades related to the credit crisis.

Bloomberg noted that McGraw-Hill tumbled the most in 25 years yesterday when it said it expected the lawsuit.

To read the Bloomberg story click here.