Bitcoin spot ETFs could trade at a premium if and when the trading begins because of the way U.S. institutions are currently allowed to handle the cryptocurrency, GTS co-Global Head of ETF Trading and Sales Reggie Browne said on Bloomberg Television.

"I think there is going to be a premium above NAV because U.S. broker-dealers can't trade bitcoin [against] cash inside their broker-dealer – some can, most can't," he said Monday. "So you’re going to have trade hedges over futures and trade it on a premium, and then take that off, and I think there is a lot of complexity there."

That complexity, together with the fact bitcoin futures are trading at a premium to the spot price, will cost investors "some crazy number," he said, offering up 8% as a suggestion.

At the same time, Browne said …