Standard & Poor's, the ratings company that downgraded theU.S. AAA credit ranking for the first time, will replace PresidentDeven Sharma with Citibank NA Chief Operating Officer DouglasPeterson.

Sharma, 55, will leave at the end of the year to “pursue otheropportunities,” S&P's parent McGraw-Hill Cos. said in ane-mailed statement. Peterson, 53, will take over Sept. 12 andSharma will work on the company's strategic review in themeantime.

S&P's Aug. 5 decision to reduce the U.S. credit rating toAA+ roiled global markets and boosted demand for Treasuries,sending the yield on the 10-year note, the benchmark for homemortgages and car loans, to a record low 2.03 percent. The NewYork-based company, which was blamed in an April Senate report forhelping fuel the credit crisis, was criticized by the world's mostsuccessful investor, Warren Buffett, who said the U.S. should be“quadruple-A.” The cut conflicted with Moody's Investors Serviceand Fitch Ratings, which kept their AAA grades.