Richard Drew/AP John S. Reed of Citicorp speaks during a news conference as Sanford Weill, chairman and CEO of Travelers Group Inc., looks on

Reed's retirement could mean a more hands-on role for former U.S. Treasury Secretary Robert Rubin, who was tapped to join Citigroup last year in a three-person chairman office, analysts said.

The move ends the power-sharing agreement Reed struck with Weill in the $70-billion merger between Citicorp and Travelers Group in 1998. Reed, 61, had led the international bank while Weill, who turns 67 in March, was head of insurance and securities firm Travelers.

The announcement also marks the latest management reshuffle at the top of Citigroup, coming less than a week after the resignation of Chief Financial Officer Heidi Miller.

Weill will be chairman and CEO but plans to work with a committee to find a successor within two years in light of his plans for his own retirement, Citigroup said in a statement.

Citigroup's stock jumped 2 to 50-1/16 on the news. Wall Street firm Morgan Stanley upgraded its rating on the stock.

"I have looked at Rubin as being a very definitive addition to the senior management team of this company since his appointment," Diane Glossman, an analyst at Lehman Brothers said. "The aspects of the company and its future that most interested Reed were different than those that captured the imagination of Sandy and Rubin."

Reed, who will formally retire at the April 18 shareholders meeting, has been a vocal proponent of the role of technology in the financial services industry. Weill is known more as a consummate deal maker, while Rubin has international clout and strong political skills.

After growing up in Argentina and Brazil, Reed joined Citibank in 1965 when it was called First National City Bank, as a planner in the overseas division. His early jobs included helping design the bank's internal management financial information system and looking at how interactive systems could be used in banking.

"My decision was a deliberate one that I have discussed fully with the board," Reed said in a statement. "From the moment we announced the merger, I committed myself to seeing through our transition from two companies into one. With the progress we have made - highlighted by the strong financial performance we achieved in our first full year as a combined company - I feel that I can now move on."

In October, Reed and Weill formed a triumvirate at the financial powerhouse by hiring Rubin as chairman of the board's executive committee.

On Feb. 23, Citigroup said Chief Financial Officer Miller is quitting to become chief financial officer of Priceline.com Inc. , an Internet company that lets people bid for everything from airline tickets to groceries.