Robert E. Rubin `60, who preceded Harvard president-elect Lawrence H. Summers as Secretary of the Treasury, has been chosen to deliver this year's commencement address.

Rubin, 62, currently chairs the Wall Street giant Citigroup, and is the third consecutive economist to serve as Commencement Day speaker. In 1999 Federal Reserve Chair Alan Greenspan spoke, and last year Nobel Prize-winning economist Amartya Sen gave the address.

"Bob Rubin has been a rare public servant, someone who has worked in a quiet, understated, yet supremely effective way to make one of the world's most complicated and important jobs seem almost easy," President Neil L. Rudenstine said.

At the Treasury, Rubin oversaw some of the greatest economic growth in U.S. history, and worked to help balance the federal budget.

Rubin also became Summers' mentor and a close friend. Despite differing styles, Rubin and Summers worked very effectively together and became one of the most formidable teams in Washington.

"The Rubin-Summers team was the strongest economic policy team we've seen in a long, long time-possibly the greatest [at Treasury] since Alexander Hamilton," economics professor Kenneth S. Rogoff said.

When Rubin decided to step down in 1999, it was his recommendation that clinched Summers' appointment as Secretary.

Rubin was also a key reference in the Harvard presidential search committee's selection of Summers last month, and was rumored to be behind numerous Wall Street job offers that came Summers' way.

Rubin met with members of the presidential search committee on numerous occasions.

"I [told] them what I said all along, that he was extremely qualified," Rubin told The Crimson in January.

Harvard Alumni Association president Scott Abell said that the incoming president did not play a role in choosing Rubin to speak.

"It is a fortuitous and very happy coincidence that Mr. Rubin accepted our invitation as the Commencement speaker several months before Lawrence Summers...was chosen to become the next president of Harvard," Abell said.

Rogoff was also quick to downplay Rubin's friendship with Summers as a reason Rubin was invited to speak.

"Actually I thought it was more like Summers was chosen because of his ties with Rubin," Rogoff quipped.

After graduating from Harvard, Rubin attended the London School of Economics before heading to Yale Law School. In 1966, the New York City native joined Goldman Sachs and Co., eventually becoming the co-senior partner and co-chair before working on Wall Street.

In 1993, Rubin went to Washington, where he headed the National Economic Council until he was named the Secretary of the Treasury in 1995.

When Rubin stepped down it was widely speculated that he'd return to Wall Street, garnering a multi-million dollar contract. Few were surprised when he joined Citigroup as one of three co-chairs.

Rubin could not be reached for comment yesterday, and it was not clear if he had decided on a topic for his speech.

Richard Zeckhauser , a professor at the Kennedy School of Government, speculated that Rubin would probably discuss world financial issues, or the privileges of a Harvard education. But he said that Rubin could speak about any number of topics.

"I can think he could surprise us," Zeckhauser said. "Since he's out of office, he's not controlled in any way [on] what he could talk about."

-Staff writer Joseph P. Flood can be reached at flood@fas.harvard.edu