This week was the second-biggest for new issues _ with five IPOs _ since the market began heating up in mid-September. There have been 22 new offerings so far this quarter, compared to just one in the final three months of last year. There are more than 90 companies in the 2010 IPO pipeline.

"This week has been a preview of coming attractions next year," said John Fitzgibbon of IPOScoop. "There is a demand for IPOs."

But while increasingly robust, this IPO market isn't for the faint-of-heart. These days, investors want to see IPOs return cash to the company. Friday's IPO of Cloud Peak Energy Inc. _ a spin-off coal producer Rio Tinto PLC's western U.S. assets _ provided a payday for Rio Tinto. Cloud Peak failed to fetch the offering price the company had wanted and its shares fell further on their first day of trading, closing down 16 cents at $14.84.

"What people really want is IPOs where the money is used to finance growth," said Francis Gaskins of IPOdesktop. "There'll be more of those companies next year."

Investors are also turning a blind-eye to smaller deals. Global Defense Technology & Systems Inc. which was looking to raise as much as $73.6 million, but was only able to collect $59.8 million after its shares failed to attract enough attention to price in its desired range of $14 to $16 per share. McClean, Va. Global Defense's shares rose 8 cents to close at $13.08 in their first trading day.

"The bar's been raised in terms of size," Gaskins said. Investors aren't paying attention to IPOs raising less than $100 million, he said.

The three companies that put in a good showing this week, Archipelago Learning Inc., 7 Days Group Holdings Ltd. and Fortinet Inc., have the qualities investors want, analysts said.

Chinese lodging chain 7 Days soared 13 percent to close at $12.50 on its debut after pricing at $11 _ the high end of the range expected by the deal's underwriters. While it hasn't shown sustainable earnings growth, turning in its first profit since 2006 in the latest quarter, it represents a "growth story IPO investors are used to," said Matt Therian of Renaissance Capital. Between 2004 and 2008, China's hotel sales grew at an average of almost 16 percent each year.

Meanwhile, sales at Archipelago Learning, a Dallas-based online education provider for students in kindergarten through 12th grade, grew 46 percent in the first three quarter of this year. The company believes it can expand despite cuts in school budgets as schools emphasize student testing and teacher accountability to comply with the federal government's No Child Left Behind Act. It's shares rose $2.27, or nearly 14 percent, to close at $18.77.

And network security provider Fortinet Inc., which jumped 33 percent in its first day of trading on Wednesday, is a leader in its field, said Gaskins. Earlier this week, IPOfinancial President David Menlow said the Sunnyvale, Calif. company was a straightforward bet for investors, with continually improving sales growth.