U.S. private equity firms, including buyout and venture capital funds, have raised $263 billion so far this year, already breaking last year's fundraising record.

Dow Jones Private Equity Analyst reported that the record-breaking money was raised by 364 private equity funds. Last year, $258 billion was raised.

"With the present momentum and a full seven weeks left in the year, we could well see fund-raising break the $300 billion mark for the first time," said Jennifer Rossa, managing editor of Dow Jones Private Equity Analyst.

Buyout and corporate finance funds are attracting the lion's share of the money, accounting for about $203 billion, or roughly 77 percent of all capital raised this year.

Last month, Ignition Partners, a Bellevue-based venture capital firm, said it raised $675 million in capital.