Microsoft CEO Steve Ballmer was not far behind at $15.2 billion, as was a co-founder of the software firm, Paul Allen, with $15 billion, much of that in other holdings including sports teams.

Mark Zuckerberg, co-founder and CEO of Facebook, though with dwindling share values, made it to 9^th position among tech billionaires with a worth estimated at $13.3 billion. Zuckerberg's fortune had been pegged at $17.5 billion a year ago, and it could have moved higher after the social network's public offering, but slid to $9.4 billion with the slump in Facebook shares, which have since seen a rebound.

Azim Premji, founder and CEO of Wipro, is placed at 9^th position, is the wealthiest non-American among the tech billionaires. His estimated fortune is $11.2 billion.

Number 11 among the tech billionaires in the Forbes list was the family of Laureen Powell Jobs, widow of Apple co-founder Steve Jobs, with an estimated fortune of $10.7 billion. Twelfth in the sector was Hasso Plattner, a cofounder of German software firm SAP ($8.9 billion), followed by eBay founder Pierre Omidyar ($8.7 billion), Google chairman Eric Schmidt ($8.2 billion) and James Goodnight of the analytics firm SAS ($7.7 billion).

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