The Wealth of the U.S.'s richest individuals exceeds the annual output of some countries.

In the October 1, 2009 Forbes article "Countries Billionaires Could Buy," Keren Blankfeld reports that the wealth of the U.S.'s richest individuals exceeds the annual output of some countries. The annual gross domestic product (GDP) is a measure of the total value of all final goods and services produced within the borders of a country during that year. (Final products are those that are not used as inputs to make other goods and services.) GDP does NOT measure a country's wealth, however. The article may be helpful in appreciating the magnitude of these people's riches. But the author is mistaken to infer that the assets of these countries (i.e. the accumulated wealth throughout history) could be purchased for the value of one year's output.

According to the article:

These American moguls could buy some of the world's economies.

Castles in France. Islands in the Caribbean. Private jets. With a collective $1.27 trillion at their disposal, the members of The Forbes 400 could buy almost anything.

How about a country? A quick glance at the CIA Fact Book suggests the individual fortunes of many Forbes 400 members are as big as some of the world's economies.

Bill Gates, America's richest man with a net worth of $50 billion, has a personal balance sheet larger than the gross domestic product (GDP) of 140 countries, including Costa Rica, El Salvador, Bolivia and Uruguay. The Microsoft (MSFT) visionary's nest egg is just short of the GDP of Tanzania and Burma.

Warren Buffett, who lost $10 billion in the past 12 months and is this year's Forbes 400 biggest dollar loser, still has a fortune the size of North Korea's economy at $40 billion. (The Oracle of Omaha probably would steer clear of that investment, though.)

One Forbes 400 member does actually run a small chunk of a state in an official capacity: Mayor Michael Bloomberg. While he is busy serving as the chief executive of New York City and grappling with its sluggish economy, his own personal balance sheet--amassed through financial information services and media company Bloomberg LP--equals the value of all the goods and services produced in South Africa's Republic of Zambia's ($17.5 billion).

Some say that land developer Donald Bren, whose assets throughout the vicinity of Orange County, Calif., include 475 office buildings, 115 apartment communities, 41 retail centers, resort properties and new housing, runs Orange County--he certainly owns most of it. And with a net worth of $12 billion, he could, in theory, buy Haiti's economy, too.

Casino mogul Sheldon Adelson's $9 billion net worth is akin to the Bahamas' GDP ($9 billion). Pierre Omidyar, founder of eBay (EBAY), the world's biggest auction marketplace, could theoretically control Somalia's market with his $5.5 billion fortune.

George Lucas, the famed Hollywood director behind the Star Wars and Indiana Jones franchises and ILM, the world's most bankable special effects shop, has a $3 billion fortune, making him worth as much as the GDP of Guyana.

Hedge fund founder David Shaw's $2.5 billion net worth parallels Belize's marketplace.

Investor John Paulson amassed much of his fortune by exploiting the real estate bubble and shorting the subprime market in 2007. Today he has a net worth of $6.8 billion--the equivalent of Montenegro's gross domestic product.

Although Eli Broad's fortune suffered because of AIG's (AIG) collapse last fall--he's lost $1.3 billion in the last 12 months--he still has a bank account that rivals Barbados' economy ($5.4 billion).

Forbes 400 members with net worths just under $1 billion still possess fortunes that could operate the economies of significant fractions of the globe. Gary Magness, who owns water rights in Colorado through his ranch holdings, has a net worth of $990 million, which barely exceeds Vanuatu's GDP ($988.5 million).

If this year's three poorest Forbes 400 members were to combine their wealth (a combined $2.9 billion), their amassed fortune would be worth more than the workings of Belize's entire economy.

The Forbes 400: An Annual Survey of the Wealthiest People in the United States

The September 30, 2009 report of "The Forbes 400 Richest Americans" shows that the economic decline has affected even the wealthy:

Almost all of America's wealthiest citizens are poorer this year.

America's super rich are getting poorer. For only the fifth time since 1982, the collective net worth of The Forbes 400 — our annual tally of the nation's richest people — has declined, falling $300 billion in the past 12 months from $1.57 trillion to $1.27 trillion.

Faltering capital markets and real estate prices, along with divorce and fraud, pushed the fortunes of 314 members down and drove 32 plutocrats off the rankings.

Hurt the most: Warren Buffett, America's second-richest citizen. The Oracle of Omaha dropped $10 billion from his personal balance sheet as shares of Berkshire Hathaway fell 20% in 12 months. He is now worth $40 billion.

Beating out Buffett for the 16th straight year as America's richest man is Microsoft co-founder Bill Gates. Sluggish Microsoft shares and declining outside investments pushed the software visionary's net worth down $7 billion in 12 months.

Rounding out the top 10 on The Forbes 400: Oracle founder Larry Ellison ($27 billion); Wal-Mart heirs Christy Walton ($21.5 billion), Jim C. Walton ($19.6 billion), Alice Walton ($19.3 billion), and S. Robson Walton ($19 billion); media maven Michael Bloomberg ($17.5 billion) and energy titans Charles and David Koch ($16 billion each).

The 10 richest Americans lost a combined $39.2 billion in the past 12 months, a 14% decline.

Other big losers include casino mogul Kirk Kerkorian, whose nest egg shed $8.2 billion in the past year. Shares of his gambling giant MGM Mirage have fallen 90% from their October 2007 high.

Also hitting the brakes: Enterprise Rent-A-Car founder Jack C. Taylor. The rental car titan's fortune is down $7 billion in a year as the travel industry slows and private-company valuations fall.

The biggest gainer is banker Andrew Beal, who tripled his net worth to $4.5 billion buying up cheap loans and assets as the markets crumbled last fall.

Membership on the list was made easier as the price of admission dropped $350 million, from $1.3 billion last year to $950 million this year, paving the way for 19 new members and 19 returnees.

Newcomers to the list include Marvel Entertainment chief Isaac Perlmutter, whose net worth soared to $1.55 billion after Disney agreed to buy the superhero outfit in August for $4 billion in cash and stock.

Other new members include Bloomberg LP co-founder Charles Zegar ($1 billion), mapping-software magnate Jack Dangermond ($2 billion) and trading titan Steven Schonfeld ($1 billion).

Former New York lawyer and accountant Jeffry Picower makes his debut on The Forbes 400 with a net worth of $1 billion. A longtime investor with Bernard Madoff, he is likely worth billions more (Picower is alleged to have extracted billions of dollars from Madoff's fund before it collapsed).

Picower and his foundation are named in a lawsuit by the liquidator for Madoff's investment business, who is seeking to recover funds allegedly obtained through "fraudulent activity." Picower claims if he knew Madoff was a fraud he would not have transferred money into Madoff accounts.

In December 2008, the Picower Foundation shut down after losing its $1 billion endowment in Madoff's Ponzi scheme. The charity had given millions to MIT, Human Rights First and the New York Public Library. Picower made his first fortune selling medical device maker Alaris in 2004.

Among those returning is venture capitalist Michael Moritz, who rode Amazon's purchase of online shoe retailer Zappos and surging Google stock back onto the list.

Divorce forced Google exec Omid Kordestani from the rankings, while R. Allen Stanford lost his billionaire status when the feds froze his assets after charging him with allegedly running an $8 billion Ponzi scheme.

Several Forbes 400 mainstays also fell off the list, including former Citigroup czar Sanford Weill, mall developer Matthew Bucksbaum and condo kingpin Jorge Perez.

Six members died, including glass giant William Davidson and newspaper maven Frank Batten Sr.

The Forbes 400 is a snapshot of wealth on Sept. 10, 2009. Gap co-founder Donald Fisher, who ranks No. 296 on our list, died Sept. 27 at his home in San Francisco at age 81.