Investors' reactions mixed as IPOs make a comeback

— -- Remember IPOs? They're back — sort of. Five initial public offerings started trading Thursday, making it the best week since December 2007 for companies selling stock for the first time, Renaissance Capital says.

But investors' reactions to the flurry of deals were uneven, as two of the five deals closed below their offering prices, showing how the comeback of new deals is likely to be rocky.

"It's not like the old times when the companies that needed the capital to emerge could (launch an) IPO," says Francis Gaskins of IPOdesktop. "Now they have to be emerging before the IPO."

It's easy to be encouraged by the uptick in deals. There have been six IPOs in September, topping the five in August and three in July, Renaissance says.

Still, Wall Street's reaction to the deals creeping out show investors are:

But that pop says more about the rush of mutual funds to invest in environmentally aware companies than the company itself, Killian says. The company is unprofitable, but funds are "piling onto this one," she says.