The words “actively managed ETF” might seem like an oxymoron in an industry founded on the premise that low-cost investment in passive indexes beats having a fund manager call the shots. But if the SEC allows some exchange-traded funds to limit public viewing of portfolio holdings, which a number of experts predict will happen over the next few months, a slew of actively managed equity ETFs could start hitting the market soon.

“A year ago, I would have questioned whether nontransparent ETFs would ever happen,” says Bill Donahue, a managing director at consulting firm Pricewaterhouse Coopers. “Now, it’s just a question of when. It could be six to nine months, or even sooner. When it happens, it will open the floodgates for others to follow.”

Morningstar’s Robert Goldsborough also sees a new era for active management on the horizon. “The SEC’s moves suggest to us that launches of actively managed nontransparent ETFs could be imminent,” he wrote in a June report. “Should one or more of these proposed structures get the go-ahead from the SEC, we anticipate that the active ETF floodgates could open, and far more traditional fund managers may subsequently seek to roll out their strategies in relatively low-cost, tax-efficient ETF wrappers.”

All this talk of opening floodgates is a result of what appear to be imminent exemptions from SEC transparency rules for some ETFs. In contrast to mutual funds, which must disclose portfolio holdings at least quarterly, the SEC requires exchange-traded funds to publish their positions daily. That requirement makes fund managers uneasy about investors mimicking their trades or front-running positions, and it’s the main reason the 87 actively managed ETFs currently on the market almost always avoid equities and gravitate toward fixed income, currencies or funds of funds.

But that could change quickly if the SEC finally grants exemptive relief to a number of companies hoping to disclose their holdings the way mutual funds do. The companies seeking permission for nontransparent ETFs include industry giants T. Rowe Price, Vanguard, Eaton Vance, State Street and BlackRock, as well as another firm, Precidian Investments. In late July, American Funds, which runs eight of the 20 largest mutual funds in the country, became the latest entrant to join the group when it filed for permission to offer nontransparent ETFs. The proposed offerings include large-cap stock funds, long-short strategies, emerging market funds and dividend-focused strategies.

This would also be welcome news for mutual fund firms, which have been experiencing outflows and losing money to passive index ETFs for the last several years, because it would allow them to add another distribution channel for active management. Donahue says retail investors, who now account for only about 4% of the ETF market, are a particularly fertile area for growth in this market.

If “smart beta” ETFs are any indication, investors seem to be open to the notion of moving beyond plain vanilla indexing, even if the cost of doing so is higher. The market for these ETFs, which include strategies such as fundamental weighting, equal weighting and low volatility, now accounts for about 18% of the total ETF universe, according to Morningstar.