Something we would expect to close:

"Arbitrage will close that gap, but it will be days and weeks," Cboe Chief Executive Officer Ed Tilly said on Bloomberg Television Monday, less than a day after launching the product.

"If you're doing a cash-settled future, it's just a bet," said Aaron Brown, a former managing director at quant hedge fund AQR Capital Management who invests in the cryptocurrency and writes for Bloomberg Prophets.

"If that's not related to any underlying physical transaction, the only people who want to do it are gamblers."

The wide arb spread is "a big issue. It's an illiquidity, it has to go away." The price gap between bitcoin and bitcoin futures won't last forever, said Dave Weisberger, CEO of CoinRoutes, a cryptocurrency data and order routing company.