Dramatic Swings on Wall Street Likely to Shred the Paper Fortunes of America's Super-rich

The turmoil on Wall Street this week has played havoc with the wealth of the United States' super-rich, threatening the position of the investment expert Warren Buffett as the country's second-richest businessman and decimating the paper fortunes of financiers and investors.

The latest list of the US top 400, published by the business magazine Forbes this week, estimated American fortunes as of the end of August. Since then the market has experienced some of the most dramatic swings ever and the list now looks like a window into a bygone world.

Earlier this year Buffett, the legendary stock-picker dubbed the Sage of Omaha after his Nebraskan home, briefly overtook Microsoft co-founder Bill Gates as America's richest man.

Since then the Dow Jones has been on a roller coaster ride, Lehman Brothers has become the world's largest-ever bankruptcy, Merrill Lynch has been forced into a shotgun wedding with Bank of America, AIG has been bailed out by the US government and Morgan Stanley sent looking for its own saviour.

Worries about the credit crunch had already reduced Buffett's fortune by $12bn (£6.6bn) over the six months to the time the list was compiled on August 29, leaving Gates in the top spot with a net worth of $57bn. Buffett is worth $50bn. Although he has a reputation for making astute financial judgments, he would have needed to be on top form over the past five days to benefit from the dramatic swings on Wall Street.

AIG's woes earlier in the year had already pushed one of the insurance group's major shareholders, Eli Broad, down to No 48 on the list with an estimated wealth of $6.7bn. A well-known philanthropist, he sold his SunAmerica business to AIG and the proceeds have helped not only his adoptive city of Los Angeles but the nation's art dealers. He owns the world's largest collection of works by Jeff Koons and once bought a painting by Roy Lichtenstein for $2.5m using a credit card. The government bailout of AIG, however, will have significantly hit his wallet since the Forbes 400 list was compiled.

It is unlikely that art will retain its value in the current slump, despite the record-breaking Damien Hirst sale earlier this week. This will come as a shock to Donald and Doris Fisher, the founders of the Gap clothing chain, who returned to the list in joint 377th place - on $1.3bn - thanks to their $1bn art collection.

The pair share their spot with the former Citigroup boss Sandy Weill, who can expect the turmoil to have hit the value of the bank's shares he still owns. The position of the Texan banker and fellow Citigroup shareholder Gerald J Ford, listed at No 355 with $1.4bn, also looks rocky.

Wall Street's crash and the demise of Lehman Brothers will have hit the $15bn fortune of 15th-placed Abigail Johnson. Her family runs Fidelity Investments, which is understood to have funds with some of the highest exposure to both the collapsed investment bank and AIG. Her father Edward is placed at No 28 with $11bn, level with George Soros.

Soros ranks highest among those in the Fortune 400 whose wealth comes from hedge funds and private equity, and it is unlikely that all the other 23 in the list who have made their money the same way will be there in a year's time.

The Bridgewater Associates boss, Ray Dalio, is ranked at No 78 with $4.5bn, while the Och-Ziff hedge fund co-founder Daniel Och is at No 95 on $3.9bn. Also at No 78 is John Paulson, who has made millions for his funds over the past year by betting against sub-prime assets. The firm's Credit Opportunities fund was up 590%, net of fees, last year.

As well as wiping out billions in paper fortunes as share prices collapse, and perhaps raising billions more for shrewd investors, the impact of the turmoil in banking is likely to hit other industries.

Particularly vulnerable is Michael Bloomberg, who is in eighth place, with $20bn. The collapses and mergers in the financial industry are likely to significantly reduce demand for the news and trading terminals that bear his name.

Google's Sergey Brin and Larry Page come in at 13 and 14 with $15.9bn and $15.8bn respectively. Lawrence Ellison, boss of Oracle, comes in third at $27bn, while spaces four, five and six are taken up with the Wal-Mart dynasty, who together control more than 39% of the grocery chain. Jim Walton comes in fourth at $23.4bn; his elder brother Robson Walton is in fifth on $23.3bn, and their sister Alice is joint sixth with $23.2bn.

Finally, the Facebook founder Mark Zuckerberg can afford a wry smile. At 24, he is the youngest member of the Forbes 400, thanks to the $15bn valuation placed on the social networking site when Microsoft took its 1.6% stake last year. His fortune puts him at number 321.