The race for the first bitcoin ETF has hit a regulatory speed bump.

In the past 24 hours, four prospective issuers withdrew requests at the SEC for approval to list ETFs based on the largest cryptocurrency. Direxion Shares ETF Trust said the regulator “expressed concerns regarding the liquidity and valuation of the underlying instruments” its proposed fund would invest in.

More than 15 bitcoin-related ETFs have been proposed since 2013. Bloomberg News

The withdrawals are the latest setback for the financial industry’s push to bring bitcoin into the investing mainstream a month after the first futures contracts began trading. Proponents speculated the derivatives would tamp down wild swings in bitcoin spot prices and open up the market to other products such as ETFs.

But the SEC has not deviated from its skeptical view of the assets. Just Friday, the regulator issued a bipartisan endorsement of a warning on digital coins, saying investors should “exercise caution” as many participants in “cryptocurrency-related investment markets are not following” securities laws. In March, the watchdog rejected the Winklevoss Bitcoin Trust ETF proposal.

Bitcoin fell 1.2% to $14,762 as of 4:18 p.m. in New York. The coin rose 1,400% last year, but ended 23% below its all-time high of $19,511, set the day CME Group launched its version of bitcoin futures.

Even amid skepticism, bitcoin mania mounts
It’s been month after month of record-breaking, confounding growth for the cryptocurrency, accompanied by regular warnings from banks about bubble speculation.

More than 15 bitcoin-related ETFs have been proposed since 2013. On Monday, Exchange Listed Funds Trust said it withdrew its application for several ETFs based on the cryptocurrency at the request of the SEC. ProShares Trust on Tuesday pulled its request to list four bitcoin ETFs “in response to a request” by the SEC. VanEck Vectors ETF Trust also dropped its request Tuesday.

Cboe Global Markets, the exchange operator that listed the first bitcoin futures, filed in mid-December for a proposed rule change to list and trade shares of the GraniteShares Bitcoin ETF and GraniteShares Short Bitcoin ETF. The application is pending.

Bloomberg News