Gates is still the richest man in America. But he was the number two gainer in dollar terms this year, with his paper wealth soaring by $11.5 billion to $72.6 billion. Casino tycoon Sheldon Adelson was third, with an $11.4 billion gain to $35.3 billion.

The gains were fueled almost entirely by rising stock prices, which boosted the value of company shares held by founders and corporate chiefs. And the wealth was spread throughout all industries, suggesting that the broad stock market gains have been the chief wealth driver this year—rather than industry-specific gains in tech, energy or other sectors.

The top 10 billionaire gainers saw their wealth increase by a combined $101.8 billion—more than the GDP's of Puerto Rico or Slovakia.

Here is the full list.

Top billionaire gainers in 2013

1.    Warren Buffett—$12.7 billion gain to $59.1 billion
2.    Bill Gates—$11.5 billion gain to $72.6 billion
3.    Sheldon Adelson—$11.4 billion gain to $35.3 billion
4.    Jeff Bezos—$11.3 billion gain to $34.4 billion
5.    Mark Zuckerberg—$10.5 billion gain to $24.7 billion
6.    Masayoshi Son—$10.3 billion gain to $19.1 billion
7.    Sergey Brin—$9.3 billion gain to $30 billion
8.    Larry Page—$9.3 billion gain to $29.9 billion
9.    Lui Chee Woo—$8.3 billion gain to $19.6 billion
10.    Carl Icahn—$7.2 billion gain to $22.1 billion

Source: CNBC