Blackstone Group is closing in on an initial public offering that would enable the US private equity group to raise billions of dollars, massively enrich its top executives and thrust the booming buy-out industry further into the public spotlight.

People close to the situation said Blackstone, which like many of its peers has been studying a listing for months, was working aggressively with bankers at Goldman Sachs to prepare a prospectus. That filing could come in the next several weeks, opening to public view financial information that has been closely guarded since financiers Steve Schwarzman and Pete Peterson set up Blackstone as a Wall Street boutique investment group in 1985.