Cameron and Tyler Winkelvoss are still working to bring the Winkelvoss Bitcoin Trust to market. Now, a U.K.-based bitcoin exchange its eying the launch of its own bitcoin ETF, which would trade in Europe.

Coinfloor, a London-based bitcoin broker, has filed plans to introduce a bitcoin ETF that would trade like a stock on Coinfloor’s exchange. Citing the Financial Times, Coindesk reports that Coinfloor’s bitcoin ETF would store bitcoins on “physical keys,” which would allow for investor access to the digital currency without the risks of direct ownership.

Coinfloor says it is the only bitcoin exchange with 100% multi-signature cold storage, “meaning that all funds being deposited, withdrawn or held in our system remain safe in underground vaults,” according to the firm.

The exchange accepts bitcoin trades in British pounds, euros, U.S. dollars and, due to a burgeoning bitcoin community in Poland, Polish zloty. Client funds are held in PKO BP, the largest bank in Poland, according to Coinfloor.

News reports did not indicate how close Coinfloor is to launching its physically-backed bitcoin ETF.