Forbes released its annual list of the 400 richest Americans today, and while there are familiar faces at the top, some billionaires had better years than others.
We combed the list to see which billionaires on this year's list had the biggest gains and losses since September 2011.
John Paulson ( -$4.5 billion ) Double-digit losses at his firm has caused his hedge fund to lose a whopping $14 billion in assets.
George Soros ( -$3 billion ) The hedge fund magnate saw a slight dip in production, but his charitable donations account for a majority of the drop-off.
Harold Simmons ( -$2.2 billion ) His Valhi holdings company dropped 30 percent in value over the last year, costing him dearly.
Anne Cox Chambers ( -$1.3 billion ) The media empress saw her net worth decline in part because of a decline in her public competitors.
Robert Stiller ( -$1.05 billion ) The innovator behind Green Mountain Coffee was forced to liquidate many of his shares in the company, reducing his net worth to roughly $250 million.
Sheldon Adelson ( -$1 billion ) Shares in his Las Vegas Sands casino decreased, causing the billion dollar loss.
Sam Zell ( -$900 million ) A lowered estimate of the value of Zell's Equity International stake caused the decrease in estimated net worth.
And now the gainers ...
Bill Gates (+$7 billion) Despite giving away billions, Microsoft's 20 percent bump in shares over the last year and Gates' private investments have led to the monetary gain.
Warren Buffett (+$7 billion) Buffett is another billionaire who's seen his company's (Berkshire Hathaway) shares go up 20 percent over the last year.
Charles Koch (+$6 billion) A rise in revenues for his chemical and Georgia Pacific properties greatly increased his net worth.
Jim Walton (+$5.7 billion) An heir to the Walmart fortune, that company's growth and his role as the CEO of Arvest Bank contributed to his gains.
S. Robson Walton (+$5.6 billion) Walmart's board chairman has received over $420 million in dividends alone over the last year.
Michael Bloomberg (+$5.5 billion) When he's not busy being mayor of New York City, Bloomberg's eponymous company saw its earnings go up 20 percent since 2011.
Alice Walton (+$5.4 billion) She also benefits from the Walmart empire, but her donations to a new art museum ensured she'd only be ninth on the list.
Jeff Bezos (+$4.1 billion) The Amazon founder and CEO saw his company register over $48 billion in 2011 sales.
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