InBev NV has made an unsolicited offer to buy Anheuser-Busch Cos. for $46.3 billion to gain half of the U.S. beer market and overtake SABMiller Plc as the world's biggest brewer by volume.

The industry's largest takeover would put InBev's Stella Artois and Leffe brands together with Budweiser, the iconic lager first brewed 132 years ago in St. Louis. In a 20-year acquisition spree, InBev has grown from a collection of family-owned Flemish beers to become the top beermaker by sales, dominating the Latin American market.

"The U.S. accounts for almost a third of world beer profit, and there is hardly any overlap" between the companies, said Marcel Hooijmaijers, an analyst at Landsbanki Kepler in Amsterdam, before the bid was announced.

The offer by InBev is 24 percent more than Anheuser-Busch's share price May 22, the day before reports of the potential takeover bid began circulating.

Anheuser-Busch shares yesterday rose $4.15, or 7.1 percent, to $62.50 at 6:18 p.m. after the close of the New York Stock Exchange. Molson Coors Brewing Co. gained $1.21, and Boston Brewing Co., the maker of Samuel Adams, jumped 82 cents.

Anheuser-Busch chief executive August Busch IV sent an e-mail to the company's beer distributors acknowledging the bid and saying a decision may take months or longer, according to the e-mail newsletter Beer Business Daily.

"As soon as we are able to relay the board's decision to you, we will do so," the newsletter quoted Busch as saying. "There is nothing you should be doing, other than continuing to focus on business as usual."

InBev — which is based in Leuven, Belgium — said on its Web site that it intends to pay for the purchase with cash.

InBev's bid follows SABMiller's agreement to combine its U.S. division with that of Molson Coors. Anheuser-Busch, the world's biggest brewer for five decades before being overtaken by InBev, has been selling the Belgian company's Beck's and other brews in the U.S. for the past year.

While InBev has operations in at least 30 countries and sells in more than 130, it generates less than 1 percent of its beer volume in the U.S. Industrywide sales in the U.S. are almost $100 billion a year, according to Euromonitor Plc.

The acquisition wouldn't increase earnings for at least three years, Goldman, Sachs & Co. analysts wrote in a note May 30. A purchase may also harm Anheuser brands should InBev try to lower costs, Deutsche Bank AG analysts wrote May 26.

A combination would save about $450 million a year in marketing, distribution and administrative costs, Credit Suisse Group AG estimated.

InBev would add Bud Light with the purchase and create a company with sales of more than $36 billion, based on 2007 revenue.