May 5 (Bloomberg) -- Yahoo! Inc. Chief Executive Officer Jerry Yang ended the day $232.7 million poorer after Microsoft Corp. withdrew its $47.5 billion takeover offer.

Microsoft CEO Steve Ballmer abandoned his bid May 3 after saying he didn't want to pay the $37 a share Yang and Yahoo's directors demanded for the Internet company. Yahoo fell 15 percent in Nasdaq trading today, the most since July 2006.

Yang, who co-founded Yahoo in 1995 with fellow Stanford University student David Filo, had 54.1 million shares as of April 2007, according to a regulatory filing. That values the shares at about $1.32 billion, down from $1.55 billion on May 2, when the stock climbed as talks between the two companies intensified.

Filo's 80.8 million shares dropped $347.6 million in value. based on today's close.

Apart from Yang, eight other members of Yahoo's board lost about $12.5 million, based on calculations from their holdings reported for April 2007.

Yahoo, based in Sunnyvale, California, fell $4.30 to $24.37 at 4 p.m. New York time in Nasdaq Stock Market trading. Microsoft, the world's largest software maker, lost 16 cents to $29.08.

Yang, 39, owns about 4 percent of the stock, while Filo has a 6 percent stake. They joined the billionaire ranks in 1999.

Yahoo spokeswoman Diana Wong declined to comment on the founders' holdings.

Billionaire List

Forbes magazine put the pair's worth at about $4 billion each before the market crashed in 2000, wiping out 86 percent of Yahoo's value. Yang was 524th on Forbes list of world's richest people published in March, with a net worth of $2.3 billion.

The board includes Chairman Roy Bostock, who had 210,695 shares in April 2007. Arthur Kern, chairman of American Media, had 730,385 shares, and Softbank Capital managing partner Eric Hippeau had about 801,958 shares. Kern and Hippeau joined the board before Yahoo's initial public offering in April 1996.

Yahoo's sales surged from $20 million in 1996 to more than $1 billion four years later as advertisers turned to the Internet to reach more people. While revenue has climbed every year since 2002, Yahoo hasn't been able to keep pace with growth at leader Google Inc.

To contact the reporter on this story: Connie Guglielmo in San Francisco at cguglielmo1@bloomberg.net

Last Updated: May 5, 2008 16:19 EDT