Conditions look ripe for a private-equity revival, but investors are still waiting for managers to show them the money.

It has been a bumpy ride for investors in publicly traded managers like Blackstone Group, whose shares fell sharply after an initial public offering at the top of the market in 2007. While stocks have rebounded to a new record and most of the firm's funds are in positive territory, Blackstone still trades 36% below its IPO price.