Craig O. McCaw, the Seattle-based financier, is reducing his stake in Nextel Communications Inc. and will give up his right to three seats on the board of a company he helped transform into one the nation's largest mobile phone enterprises.

McCaw, who owned 8 percent of the Reston-based company two years ago, will own less than 5 percent within the next two weeks as he sells his shares. With that drop, he will give up the right to control three seats on the 11-seat board of directors and will surrender the right to appoint members to the committee that names the chief executive. But, pending shareholder approval, he will keep his seat on the board through the end of his term in May 2004.

McCaw jump-started Nextel with a $1.1 billion commitment in 1995 as it changed from Fleet Call Inc., a company that owned radio licenses used by trucks and other automobile fleets, into a mobile phone company targeting high-end business customers. Nextel is now the fifth-largest mobile phone service, with about 10.1 million subscribers.

After soaring to more than $80 in 2000, Nextel shares fell to a low of $2.50 early last year. But during the past 12 months, the stock has recovered somewhat, closing yesterday at $12.47, down 42 cents, or 3.26 percent.

Earlier this week, Motorola Inc. announced that it was reducing its stake in Nextel by 23 percent, selling 25 million shares. Motorola, the world's second-largest mobile phone manufacturer and Nextel's largest shareholder until that sale, said it sold the shares to lock in gains and improve its cash position. The company reaped a $250 million pretax gain from the sale.

McCaw's plans for a series of prearranged sales of Nextel stock were first disclosed to the Securities and Exchange Commission more than a year ago. His original agreement with Nextel required him and his two designees to step down from the board if his stake droppedbelow 5 percent. But the company announced yesterday that it will allow all three to serve on the company's board until their terms expire over the next two years, as long as shareholders agree.

McCaw's investment in Nextel has been profitable, according to J. Timothy Bryan, chief financial officer of Eagle River Inc., a holding company for McCaw's investments. Bryan declined to provide details of the transactions.

"Craig has been a significant contributor to our success and has helped us become a major force in the wireless industry," Nextel chief executive Timothy M. Donahue said in a company statement yesterday.

Bryan said that because McCaw has agreed to serve on the board, his trading in Nextel shares will continue to be filed with the SEC, which demonstrates his continued confidence in the company.

"I strongly believe in Nextel's strategic vision, management's track record of execution, and the company's ability to deliver wireless products which no competitor can match," McCaw said in the company statement.

Nextel had a record-breaking 2002 in which it swung to a profit and doubled its revenue at a time when big telecommunications companies are struggling to reach break-even. But some analysts have concerns about Nextel's future. One of the company's biggest advantages is its phones' ability to operate like walkie-talkies with other Nextel phones. The "push to talk" feature has made Nextel service particularly popular with business customers in finance and construction. But in the next year other mobile phone companies are expected to introduce similar features.

"The advantage of the company is going to fade," said Vik Grover, a telecommunications analyst with Kaufman Bros.

Financier Craig O. McCaw's $1.1 billion investment in 1995 helped jump-start Nextel Communications.