NEW YORK (AP) _ Former U.S. Secretary of the Treasury Robert E. Rubin is heading to financial powerhouse Citigroup, joining top executives Sanford I. Weill and John S. Reed in a newly created three-person office of the chairman.

Rubin was also elected to the board of directors of Citigroup, the nation's largest financial company announced today.

Rubin will serve as chairman of the executive committee of the board and will work with Reed and Weill, the chairmen and co-chief executive officers of Citigroup, as a third chairman of the New York-based company.

Rubin, 60, left the Clinton administration in July. He was one of the wealthiest members of Clinton's cabinet, spending 26 years on Wall Street and ultimately becoming chairman of investment bank Goldman Sachs.

He will participate in strategic, managerial and operational matters, but will not handle day-to-day matters.

``Bob has the best job in the company because he has no line of responsibility,'' Reed joked during a press conference.

Indeed, though Rubin's name has floated on Wall Street as a possible successor to the chief executive post at Citigroup, he put an end to the speculation.

``I did not want to be and will not be a CEO,'' he said.

The board of directors of Citigroup was formed in October 1998 through the merger of Citibank and Travelers Group.

Earlier this month, Citigroup reported that its profits for the third quarter more than tripled as the company saw business boom in its global and investment banking units, which had suffered the most during last year's market turmoil.

Citigroup provides some 100 million consumers, corporations, governments and institutions in 100 countries with a range of financial services, including consumer banking and credit, corporate and investment banking, insurance, securities brokerage and asset management.

Shares of Citigroup jumped 3 percent on the news, rising $1.56 1/4 to $49.37 1/2 in trading on the New York Stock Exchange.