Cameron and Tyler Winklevoss, thought to be among the largest holders of bitcoin, said the advent of futures is just the beginning of a phase of greater acceptance for the cryptocurrency that is often derided as a bubble.

“We think it’s the starting gun to a whole new phase of liquidity and price discovery and sophisticated entrance to the market,” Tyler Winklevoss said during a Bloomberg Television interview.

The Winklevoss twins are co-founders of the Gemini exchange, which Cboe Global Markets Inc. is using as the basis for the daily settlement for the bitcoin futures that began trading this week.

The Winklevoss brothers said in 2013 that they owned almost $11 million worth of bitcoins. If they retained that stake it would be valued at about $950 million today, according to the Bloomberg Billionaires Index. The ranking calculates they each have a $1.1 billion fortune as of Monday after taking into account other assets.