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.