It's been a five-year bull market in billionaires.
Since the market bottom in 2009, America's billionaires have seen their fortunes and numbers soar to new records. There are now around 500 billionaires in America—up from around 360 in 2009, according to Forbes and Wealth-X.
Their combined fortunes have nearly doubled, to more than $2 trillion today from around $1.2 trillion in 2009, according to Forbes and Wealth-X. Most of that came from stock gains.
(Read more: Countries with the most multimillionaires)
For perspective, America's roughly 115 million households have gained about $14 trillion in stock wealth since 2009. So America's billionaires gained 7 percent of all of America's gain in household wealth from stocks.
This helps explain why the broad economy is still so weak even if household wealth and stock wealth is at all-time highs. So who were the biggest gainers?