In a deal that will further shake up the region's supermarket industry, Richfood Holdings Inc., a food distributor that owns Shoppers Food Warehouse, said yesterday it has agreed to be acquired by Supervalu Inc.

Under terms of the deal, Supervalu of Minneapolis -- the nation's largest grocery wholesaler -- will pay $18.50 a share, or about $883 million in cash and stock, and assume $642 million of the Richmond-based company's debt. The Richfood acquisition is projected to close in late summer or early fall.

Following the midday announcement, Richfood's shares, which have slumped over the past year, rose $2 a share to close at $16.87 1/2 in trading on the New York Stock Exchange. Supervalu rose 50 cents a share, to $24.81 1/4, on the NYSE.

The purchase gives Supervalu, whose 345 stores are concentrated in the Midwest, a powerful presence in the mid-Atlantic and a springboard for expansion in the Baltimore-Washington market.

By snapping up Richfood's 55 Shoppers Food Warehouse and Metro stores in this region, as well the company's 38 Farm Fresh stores in Tidewater, Supervalu will boost its annual retail food sales by about 35 percent, to $7 billion.

Competitors Giant Food Inc. of Landover and Safeway Inc., the top two grocery chains in the Washington area, said yesterday they were not surprised by Supervalu's announcement. But they acknowledged that Supervalu's deep pockets would make the continuing fight for market share here even more challenging.

"The supermarket industry is very competitive, and we continue to see consolidation in every sector, from wholesalers to retailers to brokers," said Gregory TenEyck, a spokesman for Safeway. "We feel we're well positioned in this market."

"We're not afraid of competition," said Hans Gobes, a spokesman for Royal Ahold NV, a Dutch grocery conglomerate and owner of Giant Food, the region's largest supermarket chain.

Michael W. Wright, Supervalu's chief executive, said in an interview yesterday that he has been eager to gain a foothold in the Baltimore-Washington market. And already, he is looking to step up expansion plans for the Shoppers and Metro chains.

"Our intentions are to grow them at a significantly faster pace than Richfood, simply because we have a larger capital base," said Wright, who added that it was too early to provide details.

For Richfood, the deal could not have come at a better time, industry observers said. The wholesaler has been hurt by consolidation in the grocery retailing industry, which has left it with fewer supermarket chains as customers. For example, in April Richfood announced that it had lost a key supply contract with Pennsylvania's Giant Food Stores Inc., a unit of Royal Ahold.

"It was certainly not a doomsday scenario by any stretch," said Lee Wilder, an analyst with J.C. Bradford & Co. in Atlanta. "But I think the company wasn't satisfied with the stock valuation, and certainly shareholders were a little grumpy as well."

Supervalu, which had $17.4 billion in total sales last year, operates stores under the Cub Foods, Shop 'n Save and Bigg's banners. Its closest stores to Washington are the Shop 'n Save supermarkets in Pennsylvania, a company spokesman said.

"This is a very good strategic fit," said Jeff Metzger, a grocery industry expert and publisher of Food World in Columbia, an industry publication.

Richfood chief executive John E. Stokely said in an interview yesterday that he plans to leave the company following the acquisition. But Supervalu officials do not plan to close stores or cut employees, he said.

"They've told us they acquired us for the assets that are here," Stokely said.

Most industry observers credited Stokely and his management team with successfully reengineering Richfood and making it less dependent on the wholesale business.

Although Stokely said he and his team had done an "excellent job of navigating through pretty tough times," he said the company also recognizes that it must be much larger to compete with mammoth firms such as Ahold.

The company also faced challenges in the Tidewater market, where many of its Farm Fresh stores needed a costly overhaul, said Kenneth M. Gassman Jr., an analyst with Davenport & Co. in Richmond.

"It has been a challenge to turn around Farm Fresh," Gassman said. "They've got some really good stores and they've got stores that really need a major face lift."