Nasdaq Stock Market Chairman Frank G. Zarb said Thursday he is stepping down after more than four years at the helm.
Zarb, 66, also resigned as chairman of the National Assn. of Securities Dealers, Nasdaq's parent organization.
Hardwick "Wick" Simmons, the market's chief executive, will succeed Zarb as chairman of Nasdaq, while Robert R. Glauber, CEO of NASD Inc., will take over Zarb's position there.
The moves, approved Thursday at an NASD board meeting, will take effect in September.
Zarb will remain chairman of Nasdaq Europe and will act as an advisor to the NASD. He also is weighing private-sector opportunities.
"I am not going to retire," Zarb said. "I have another career ahead of me somewhere. I am looking at a number of things, which are all attractive."
Zarb, who took charge at Nasdaq in February 1997, steered the market through some of its most difficult times--the Justice Department probe into Nasdaq traders--and also perhaps its most triumphant--the Internet stock boom that brought Nasdaq its greatest prominence.