DUBAI, United Arab Emirates - The head of private equity giant Blackstone Group said Wednesday the industry's worst days have passed as he confirmed plans to cash in on up to eight of the firm's companies "in the near future."

And although concerns remain about the strength of economic growth, especially in the U.S. and parts of Europe, new investment opportunities are beginning to emerge, Blackstone Chairman and CEO Stephen Schwarzman said.

"It looks as if a bottom has been reached," he said, adding that the world's financial system is in "a radically different place" from its precarious state a year ago.

Renewed optimism from Blackstone and other big private equity firms reflects growing confidence on Wall Street that a lasting economic rebound is on its way.

In a sign of the new outlook, Blackstone is preparing to list shares for as many as eight of the companies it now owns.

Plans for the expected initial public offerings were earlier revealed in media reports citing unnamed sources and a confidential letter to investors, but had not been publicly confirmed by Blackstone.

The planned listings include Blackstone's Team Health hospital staffing business.

Blackstone ranks among the world's largest buyout firms, with $93.5 billion assets under management. Its portfolio includes stakes in German telephone giant Deutsche Telekom, newspaper publisher Freedom Communications, casino operator Harrah's Entertainment and the Hilton hotel chain.

Speaking to reporters after his Dubai speech, Schwarzman said the companies being prepared for possible listings are "spread across a variety of sectors" and geographic areas. He declined to identify the companies, citing legal advice.

Plunging stock markets all but killed the market for new stock offerings last year as nervous investors flocked to safer assets like cash and government bonds.

Now the mood is shifting. Discount-store chain Dollar General Corp. laid out plans in August to go public. It was bought in 2007 by private equity firm Kohlberg Kravis Roberts & Co. and other investors.

IPOScoop.com founder John Fitzgibbon said it was not surprising private equity firms - which typically take over companies using large amounts of debt with the aim of reselling them at a profit - would look to roll out stock offerings now, given the recent sharp gains in the stock market.

"They're like olives in a bottle," Fitzgibbon said of the IPOs.