NEW YORK (CNN/Money) - Rick Belluzzo will step down from his role as president and chief operating officer of Microsoft Corp. as part of a broader change in the company's organizational structure, the software maker announced Wednesday.

Under the new structure, the leaders of each of Microsoft's core business units will have comprehensive operational and financial responsibility and greater accountability, the company said.

Rick Belluzzo

Belluzzo, who was named to the post in February 2001, will phase out his role as president and chief operating officer on May 1, although he will continue to work at the company through September to ensure a smooth transition, Microsoft said.

"Rick has worked closely with me analyzing the company's structure to determine how we could improve our internal processes and maximize opportunities for growth," said Microsoft CEO Steve Ballmer.

"We realized we needed to give our core leaders deeper control and accountability in the way they run their businesses, while at the same time ensuring strong communication and collaboration across the business units," Ballmer added. "This is the right decision for Rick, but the company will certainly miss his leadership and experience."

Moving forward, the heads of Microsoft's core businesses -- Windows Client, Knowledge Worker, Server & Tools, Business Solutions, CE/Mobility, MSN, and Home & Entertainment -- will comprise a leadership team reporting to Ballmer.

Shares of Microsoft (MSFT: Research, Estimates) fell 97 cents to $56.33 on Nasdaq Wednesday ahead of the announcement, which was made after the close of trading. The stock was up 50 cents at $56.83 in extended-hours trade.