This year, as bitcoin, the largest cryptocurrency by market value, hit an all-time high, at least 18 applications for bitcoin-based exchange-traded funds, or ETFs, were filed wth the Securities and Exchange Commission.

None have been approved yet, and it's unlikely that a physical bitcoin ETF will be approved this year, Todd Rosenbluth, head of ETF and mutual fund research at CFRA, tells CNBC Make It.

However, SEC chairman Gary Gensler recently signaled that he would be open to considering a futures-based bitcoin ETF ⁠under strict rules.

A physical ETF holds the underlying assets or securities on which its value is based. In comparison, a futures-based ETF tracks futures contracts, providing exposure to an asset without taking direct ownership. In this case, a physical bitcoin ETF would hold bitcoin and track its price, while a futures-based bitcoin ETF would track bitcoin futures contracts.

Following Gensler's speech, a handful of firms filed for futures-based bitcoin ETFs with the SEC.

But even though Gensler seems more comfortable with futures-based bitcoin ETFs than physical ones, they are likely still far off. "I expect a futures-based [bitcoin] ETF approval is more likely to occur in 2022 than in 2021," Rosenbluth says.

This is likely due, in part, to SEC concerns. Along with worry over fraud and volatility within the cryptocurrency space, the SEC may also be concerned about how demand for a physical bitcoin ETF would impact the overall market.

Futures-based bitcoin ETFs would also come with unique risks, including that they do not necessarily track the price of the underlying security and come with higher costs, Rosenbluth says.

Steps for SEC approval

So what does all this mean for investors? Not much just yet.

Just because there are numerous potential ETFs doesn't mean they are more likely to be approved any more quickly, Rosenbluth says. "There's multiple steps in the potential approval process, and each product is often at different stages of that approval process."

At this time, the SEC is likely seeking more information about each potential fund, he says. And based on Gensler's recent comments, it seems the SEC is looking to further regulation within the cryptocurrency space first.

While investors may see many headlines regarding bitcoin ETF filings or of updates within the approval process, this doesn't necessarily mean anything, Rosenbluth explains.

"I wouldn't get too focused on where we are, if the SEC is going to approve something or not. Until they approve something, there's nothing an investor can do," he says. As of now, "be patient."

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