The technology bubble popped a decade ago, but the venture-capital industry that helped finance the boom stayed largely intact. Now venture-capital firms are going through their own brutal culling.

Venture firms are struggling to raise new cash, hampered by poor investment returns and a difficult economy. Last year, 125 venture funds in the U.S. collected $13.6 billion, down from 203 funds that raised $28.7 billion in 2008 and down from 217 funds that raised $40.8 billion in 2007, according to data tracker VentureSource.

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