He will return to Harvard as a visiting professor in its Law School.

Mr Glauber had been a professor at the Harvard Business School and a lecturer at Harvard's Kennedy School of Government before becoming NASD's CEO in 2000 and its Chairman in 2001.

As announced in January, Mr. Glauber will be succeeded by Mary L. Schapiro, NASD's Vice Chairman and President of its Regulatory Policy and Oversight Division.

"I came to NASD six years ago with the goal of transitioning the organization away from owning markets, and focusing it solely on its regulatory mission," Glauber said. "With NASD's recent sale of its last remaining stake in NASDAQ and with the SEC approval of NASDAQ's request to operate as an exchange beginning August 1, NASD has succeeded in making that transformation. Leaving now will allow me to join the Board of Directors of Freddie Mac, which I anticipate doing in September, consider a couple of other corporate board opportunities, and return to Harvard a bit sooner."

"I am extremely proud of everything the NASD team has accomplished over the last six years, in particular NASD's vital role in rebuilding public confidence in the securities markets after the dramatic downturn in 2000. I know Mary will lead the organization to even greater heights during her tenure."

Raymond ("Chip") Mason, chairman of the NASD Corporate Governance Committee and Chairman and CEO of Legg Mason, said, "The entire board is grateful for the job Bob has done. He steered NASD through a most critical time for securities regulators, leaving it with an unchallenged reputation for protecting investors and in the strongest financial condition. And, with its complete separation from owning for-profit markets, NASD is extremely well positioned to continue and build on its mission with energy and integrity. We understand his decision to leave a few months early and we thank him for his important service and wish him all the best in his future endeavors."