The Chicago Board of Exchange has withdrawn a proposed rule change that would have allowed the listing and trading of a Bitcoin-backed exchange traded fund.

The BZX Exchange, an equities exchange operated by the CBOE, proposed last June a rule change to list a new Bitcoin ETF offered by Van Eck Securities and SolidX Management. On Wednesday, BZX filed a notice with the Securities and Exchange Commission that it had withdrawn the proposal on Tuesday, without offering an explanation for the action.

On CNBC, Jan Van Eck, CEO of the ETF provider, attributed the move to the government shutdown, which has limited the SEC’s operations to staff managing emergency situations. VanEck and SolidX had been discussing the agency’s concerns about a Bitcoin-backed ETF, given Bitcoin is an asset traded on exchanges over which the SEC has no authority.

“The SEC is affected by the shutdown. We were engaged in discussions with the SEC about issues of custody and the market manipulation of prices,” Van Eck said. “And that had to stop. So instead of trying to slip through or something, we had the application pulled. We will refile and re-engage in discussions when the SEC gets going again.”

When CNBC’s Bob Pisani noted that “you faced the prospect they would have turned you down anyhow” because of the agency’s concerns, Van Eck said, “Absolutely. We think we have solid answers to those and we need to demonstrate that clearly. But we obviously can’t have meetings while they’re shut down.”

Last year, the SEC rejected several attempts to list Bitcoin-backed ETFs, including those from ProShares, GraniteShares and the Winklevoss twins, citing concerns about the potential for exposing their investors to fraud and market manipulation.