Adidas-Salomon AG, the world's second-largest sporting-goods company, has agreed to buy Reebok International Ltd. for about $3.8 billion to narrow the gap with Nike Inc.

The purchase would double Adidas's sales in the United States, the world's biggest market for sports gear. Adidas, whose shoes are worn by soccer star David Beckham, will have about 20 percent of the U.S. market, still behind the 40 percent held by Nike, whose endorsers include golfer Tiger Woods.

"The U.S. market is historically where they've been under-represented and it's been difficult to gain share," said Mark Hargraves, who helps manage $7.1 billion, including Adidas shares, at Framlington Group PLC in London. "It propels them up."

The combined company would have about $11.1 billion in sneaker and sports-equipment sales compared with Nike's $13.7 billion. Adidas had about $3.33 billion in shoes sales last year, while Nike had about $7.3 billion.

Under the deal, Adidas would gain the license to outfit the National Football League and the National Basketball Association. Reebok chief executive Paul Fireman, who built a small British shoemaker into a company with $3.78 billion in yearly sales, has been focusing on revamping the company's image and luring teens after Reebok shares dropped to their all-time low of near $7 in 2000.

He was active in helping to push for the company's 10-year separate exclusive agreements with the National Basketball Association and the National Football League. He's also signed basketball star Allen Iverson and rappers such as 50 Cent and Jay Z to marketing agreements and introduced sub-brands such as rbk to give Reebok a hip image.

Adidas chief executive Herbert Hainer said he doesn't expect a "significant workforce reduction" after the acquisition as he intends to have the two businesses run separately. Fireman, who founded the company in the 1970s, will continue to run the brand.

Adidas is offering $59 for each share of Canton, Mass.-based Reebok, 34 percent more than Tuesday's closing price.

Fireman stands to make about $437.8 million from the deal. Fireman owned about 7.4 million Reebok shares as of June and his wife, Phyllis Fireman, had about 6 million shares as of February, according to Securities and Exchange Commission filings. Phyllis Fireman may make $355.2 million from the planned sale.

Shares of Reebok reached their highest level since the company's 1985 initial public offering, rising $13.19, or 30 percent, to close yesterday at $57.14 in New York Stock Exchange trading.

Adidas's stock hit a seven-year high, rising $13.47, or 7.4 percent, to close at $195.94 in Frankfurt.

Adidas-Salomon chief executive Herbert Hainer, flanked by Adidas- and Reebok-jacketed mannequins, says he does not expect significant job losses after the Reebok acquisition.