Deven Sharma will step down as president of ratings agency Standard & Poor's to work on the company's strategic portfolio review before leaving the company at the end of the year.

Sharma will be replaced as president of the ratings agency by Douglas Peterson, chief operating officer of Citibank effective September 12, S&P's parent company McGraw-Hill Companies Inc said in a statement.

The company said it began a search for a new president for S&P after the company split S&P into two separate organizations at the end of last year.

The Financial Times, which first reported news of Sharma's resignation, said his resignation is not related to S&P's downgrade of the United States' credit rating or reports that the agency is being probed by the U.S. Justice Department in connection with its ratings of mortgage securities.

S&P has been under fire from lawmakers, market players and the U.S. Treasury Department since its decision to cut the U.S. credit rating earlier this month, and just last week, news emerged that the Justice Department is investigating the firm over its actions on mortgages leading up to the financial crisis.

The board of McGraw-Hill Companies made the decision to replace Sharma at a meeting where it also discussed its ongoing strategic review on Monday, the Financial Times said.

McGraw-Hill directors and executives met on Monday with Jana Partners LLC, a hedge fund, and the Ontario Teacher's Pension Fund to hear their arguments that the company should be broken up.

(Reporting by Abhishek Takle in Bangalore; Editing by Gary Hill)