Somewhere, Steve Schwarzman is smiling. And Henry Kravis is busy taking notes.

Shares of the Blackstone Group, which has led some of the biggest buyouts of American companies, jumped 18 percent at the opening of trading in its shares. The shares, priced at $31, were rising as high as $37.50 in morning trading, before slipping to $35.79 at midday.

Demand for the new stock was heavy, with an estimated 33 million shares changing hands in early trading.

"I think it’s attractive at these prices," David Joy of Riversource Investments, told CNBC.  "It has not spiked as people feared. I think it’s an attractive offering at these levels in the secondary market."

Other analysts, however, pointed to developments that might have weighed on Blackstone's shares. Its  tax bill may be increased in the future, thanks to legislation introduced in the Senate last week, and the cost of debt is rising. Buyouts of companies typically involve leverage -- taking on huge debts.

 “What’s happening is pricing is affected by the L part of LBO,” Arthur Hogan, chief market analyst at Jeffries & Co., told the Financial Times. “We’ve seen significant rises in interest rates in recent weeks and that makes some deals less attractive.”

The $4.13 billion debut of Blackstone was the biggest American initial public offering since Traveler's in 2002. (And yet while bigger than Google's $1.9 billion I.P.O. in 2004, it was smaller than the European listing of a Kohlberg Kravis Roberts affiliate in Amsterdam last year.)

Blackstone’s first day of trading was not as impressive as that of the first manager of private equity and hedge funds to list in the United States: Fortress Investment Group.  Shares of Fortress jumped 84 percent on its debut in February. That stock, however, has fallen 14 percent since and was down more than 4 percent today.

How Blackstone performs today may determine whether rivals like Kohlberg Kravis Roberts, which has reportedly hired bankers for an offering, and Carlyle Group go ahead with IPO's of their own. The hedge fund manger Man Group of Britain also plans a listing of its American brokerage arm on the N.Y.S.E.

So who are the winners in Blackstone's I.P.O.?

 For one, there is Blackstone’s new partner, the Chinese government, which invested $3 billion in the firm last month. China gets a conduit to the top deal makers and has an  opportunity to get a higher return on some of its immense cash reserves.

And then there is obviously Schwarzman, who cashes out more than $670 million from the offering and keeps a 24 percent in the firm.

 But Tom Wolfe, Portfolio contributor who has written about the new new money, was on the floor of the exchange, and said, according to the FT Alphaville blog , that “we “may be witnessing the end of capitalism as we know it.”