Actively managed exchange traded funds have been hyped as the industry’s next big growth area, but so far assets represent a small portion of the overall business.

Despite regulatory hold-ups and portfolio disclosure issues, many investment managers are lining up to list active ETFs.

“In some cases, where you have the secret hidden sauce, it’s better in a mutual fund,” said Greg Friedman, managing director of products for Russell’s ETF business. “I think the mutual fund and the ETF still stand as a complement to each other.”

James Armstrong for Traders Magazine reports that there are about 40 actively managed ETF trading now, in the U.S. This opens up the space for opportunity and market share as the interest in these funds escalates.