New York/Washington: Ratings agency Standard and Poor's on Tuesday announced that Deven Sharma, the company's Indian-origin President who was at the helm of affairs when S&P downgraded the United States' credit rating, will leave the company by the end of the year.

Taking Sharma's place will be Citibank Chief Operating Officer Douglas Peterson, 53, who will become President of Standard & Poor's effective from September 12.

Sharma, 55, will take on a special assignment working on S&P's strategic portfolio review "until the end of the year, when he will leave the company to pursue other opportunities," S&P's parent company McGraw Hill said here.

Sharma joined Standard & Poor's in 2006 as Executive Vice-President, Investment Services and Global Sales, and was named President in 2007.

Before joining S&P, he was Executive Vice-President, Global Strategy, at The McGraw-Hill Companies for five years.

He had joined the McGraw-Hill Companies in 2002 from Booz Allen Hamilton, a global management consulting company, where he was a partner.

Announcing the change, McGraw-Hill Companies Chairman, President and CEO Harold McGraw said he had turned to Sharma four years ago during one of the "most difficult times facing S&P in the midst of the financial crisis".

Sharma's background as head of S&P's investment services and head of McGraw-Hill's global strategy "brought the right kind of skills to address the situation", McGraw said.

"I particularly want to thank Deven for his dedicated leadership of S&P. Today, S&P is a stronger company, whose 1,300 global analysts are sharply focused on the quality, independence and transparency of S&P's research and analytics," McGraw added.

Sharma said, "It has been a privilege to serve as the President of S&P and I am proud of what we as an organization have achieved over the past four years. As McGraw-Hill continues its portfolio review, I will work closely with the leadership team to find ways to create even more shareholder value."

Standard & Poor's was split into two separate organisations last year -- S&P, the credit ratings service, and McGraw-Hill Financial -- to enable both organisations to serve investors and customers more effectively.

"Sharma assisted us with the creation of these two high-growth segments and was then ready for new challenges. Accordingly, we began a process to identify a new leader for S&P," the company said.

Sharma was thrust into the international spotlight when S&P made its unprecedented decision to downgrade the US long-term sovereign credit rating from the top-notch 'AAA' level for the first time ever since a rating was assigned to the world's largest economy.

Sharma led from the front and defended S&P's move when the US administration took up cudgels against the ratings agency, terming its analysis flawed and questioning its credibility and integrity.

He did his schooling in Dhanbad district of Jharkhand.

McGraw said S&P will continue to produce ratings that are comparable, forward-looking and transparent.

Prior to his current role, Peterson was the CEO of Citigroup Japan from 2004 to 2010, where he oversaw the entire franchise, covering capital markets, corporate and investment banking, global transaction services and retail banking.

He was previously chief auditor of Citigroup from 2001 to 2004, where he led the enterprise-wide integration of the internal audit teams after the merger of Citicorp and Travelers.