Blackstone Group LP raised $21.7 billion for the world’s biggest private-equity fund, just as a global credit crunch slows leveraged buyouts.

The fund is more than triple the $6.45 billion pool Blackstone raised five years ago, and tops the $20 billion amassed by Goldman Sachs Group Inc. in April. Shares of New York-based Blackstone, which held an initial public offering in June, rose as much as 4% after it announced the closing of Blackstone Capital Partners V in a statement yesterday.

Blackstone has used the fund to buy companies from Nielsen Co. to Hilton Hotels Corp., helping fuel a record $707.8 billion in private-equity transactions so far this year, data compiled by Bloomberg show. The pace of deals has slowed by a third since June, as investors who’d eagerly snapped up the loans and bonds used to fund leveraged buyouts refused to buy debt for takeovers including Alliance Boots Plc and ServiceMaster Co.

“The credit markets may be shut for now, but they won’t be shut forever,” said Steven Kaplan, a professor at the University of Chicago who studies private equity. “The private-equity firms have a ton of money, and they’re not going away.”

Blackstone, which started to plan the fund in 2004, has already committed to spend two-thirds of the money, the firm said in the statement. A private-equity firm typically takes several years to invest the money in an individual fund.

Blackstone shares rose 37 cents, or 1.5%, to $25.27 at 4 p.m. in New York Stock Exchange composite trading. The stock earlier yesterday gained as much as gained $1. Before yesterday, the stock had declined 20% since the firm’s $4.75 billion initial public offering in June.

Blackstone’s IPO, the biggest in America this year, and co-founder Stephen Schwarzman’s high profile — he held a birthday party in February that featured Rod Stewart among the entertainers — have drawn scrutiny never seen around private equity. The U.S. Congress is weighing measures that may more than double the amount of taxes buyout firms pay.

Virgin Media Inc. Tuesday postponed a planned sale of the company, and Cadbury Schweppes Plc last month delayed the sale of its American drinks division as banks struggle to find investors willing to buy an estimated $400 billion in debt related to LBOs, according to estimates from Baring Asset Management.

Mr. Schwarzman and co-founder Peter Peterson started their firm 22 years ago and now control companies with more than 500,000 employees and $90 billion in annual sales. The firm’s deals this year include the $19.9 billion purchase of Sam Zell’s Chicago-based Equity Office Properties Trust and the $20 billion takeover last month of Hilton, the second-biggest American hotel chain.

The Hilton transaction was announced as the credit revolt took hold. While other deals have closed after forcing the investment banks that financed the deals to hold bridge loans, the Beverly Hills, Calif.-based company said Tuesday in a filing with the U.S. Securities and Exchange Commission filing that Lehman Brothers Holdings Inc. and Merrill Lynch & Co. had joined a financing group that already included Goldman Sachs and Morgan Stanley.

Blackstone’s latest fund is bigger than the $16 billion pool Kohlberg Kravis Roberts & Co. is raising, and the $15 billion fund David Bonderman oversees at TPG Inc. It’s larger than any European buyout fund, topping London-based Permira Advisers LLP’s 11.1 billion-euro ($15.3 billion) pool.

Blackstone said a year ago it had initially gathered $15.6 billion for the latest fund, and in January, Mr. Schwarzman said his firm would seek as much as $20 billion for the fund.

“The record-breaking amount of capital at our disposal allows us to continue our leadership role in private-equity investing on a global basis,” Mr. Schwarzman, 60, said in yesterday’s statement.

The firm has reaped average annual net returns of 23% from their buyout funds. The firm’s assets under management rose 12% to $88.4 billion between March 1 and May 1.