Private markets: The next big thing

But there can be some tradeoffs. In exchange for a less stringent regulatory scheme, companies that privately place their shares may risk a lower valuation since there are fewer buyers available. New trading platforms can also generate uncertainty among investors.

But some say demand is so high for shares of hedge funds and private equity firms that these companies don't take much of a hit, if any at all, for choosing a private placement.

"There's such tremendous institutional investor interest in their shares that even if they use a non-standard format, there isn't much of a discount," said Roger Ehrenberg, president of Monitor110, a firm that caters to institutional investors.

A consumer-oriented brand is more likely to lose out from a lack of retail investors, said Ehrenberg. "But when you're talking about an OakTree or Apollo, these are the sorts of companies where the most interest is driven by institutions in the first place."