Microsoft co-founder Bill Gates is trying to give away his fortune. But he may have to try a little bit harder.

Microsoft co-founder Bill Gates

According to the Bloomberg Billionaires Index, Gates added $7 billion to his net worth during 2012, making him the second richest person in the world and the richest American tech billionaire.

The rise in Gates’ net worth comes even as Microsoft’s stock, which accounts for less than 20 percent of the billionaire’s fortune, rose just 2.9 percent last year.

Amazon.com founder Jeff Bezos also saw his net worth rise, driven largely by the 45 percent gains in the online retailer’s stock in 2012. That means Bezos is worth more than the Google co-founders, and ranked 20th on the list.

Carlos Slim, the Mexican telecommunications mogul, was the richest person on the planet with an estimated net worth of $76.4 billion, according to the report. (Full list here). In total, those on the Bloomberg Billionaires Index added $241 billion during 2012, and just 16 of the 100 people on the list saw their net worth decline in 2012.

Previously on GeekWireThe top tech stocks of 2012: Shares of Expedia take off

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