U.S. Securities and Exchange Commission Chair Gary Gensler is signaling a pathway for approving a Bitcoin exchange-traded fund, a move that crypto enthusiasts say is crucial for taking tokens to the mainstream.

Gensler said that an ETF that complies with the SEC’s strict rules for mutual funds could provide investors with necessary protections. Speaking in his first major speech on cryptocurrencies, Gensler also signaled an openness to an ETF focused exclusively on Bitcoin futures, which are offered by CME Group Inc. and require that investors put down substantial margin to trade.

“Given these important protections, I look forward to the staff’s review of such filings, particularly if those are limited to these CME-traded Bitcoin futures,” he said in Tuesday remarks prepared for the Aspen Security Forum.

The SEC under Gensler and his predecessor Jay Clayton has repeatedly balked at green-lighting a crypto ETF, with the agency raising concerns over transparency and potential for manipulation in the Bitcoin cash market.

Most pending ETF applications have been filed under 1930s laws that allow stock exchanges to list products. Gensler is hinting that he’d like to see a filing that seeks approval through a 1940 law that governs mutual funds.

The distinction isn’t just academic. The law for mutual funds has much stronger investor protections and requires funds’ boards to provide close oversight of the investments, lawyers said. The additional demands include a mandate that funds have independent boards and a restriction on affiliated people trading shares in the ETF.

The added strictures can be a benefit for those hoping to list a product but some may find them too burdensome, said David Grim, a law partner at Stradley Ronon in Washington who previously led the SEC’s investment management division.

“It comes with costs,” he said. “Depending on your sort of business model and your financing, maybe that’s too much or that’s not what you want to do.”

Gensler’s ETF comments could add to a debate over whether cryptocurrencies are securities. That’s because some existing ETFs that track commodities or currencies aren’t regulated under the mutual fund rules, according to brokerage regulators. U.S. officials have classified Bitcoin as a commodity.

There are at least half a dozen Bitcoin ETF applications now before the SEC. In his speech, Gensler said that while he’s interested in Blockchain technology and sees potential value in crypto, he plans to move aggressively to protect investors in the space.

“We just don’t have enough investor protection in crypto,” he said. “It’s more like the Wild West.”

The worries mirror concerns that Gensler laid out in an exclusive interview with Bloomberg Businessweek in which the SEC chief said he won’t compromise on protecting investors in setting out a regulatory framework.