Bitcoin futures trading at Bakkt has broken another milestone this week. Following last week’s record-breaking haul for trading volume—over the last two weeks, open trading interest has rocketed from under $1 million to a record $6.5 million yesterday.

In comparison to daily trading volume—that indicates the volume of trades that were executed on the platform on any given day—open interest is the total sum of all traders with active “Long” or “Short” trading positions open at the CFTC regulated exchange.

Interestingly, the recent surge in trading interest could indicate a longer-term bullish outlook for the future’s platform. In contrast to daily exchange volume—that can often see large spikes due to sharp movements in Bitcoins price—open interest is more of a stable measure to understand how interested Bakkt’s predominantly US institutional trader base is to the Bitcoin-settled futures product.

After going live in late-September, Bakkt has significantly ramped-up activity on its platform. After registering $4.3 million and $0.8 million in volume and open interest respectively in its first full week of trading—last week the platform hit a record sum of $124 million in volume and $4.3 million in open interest. The most recent daily surge (+42%) in open interest is also surprising, given that the growth in trading volume seems to have cooled off as of late.

However, don’t get too excited just yet Bitcoiners.

According to trader Alex Krüger, Bakkt Bitcoin futures are in reality only 63% backed by Bitcoin according to the market documentation. The other 37% is backed up by fiat in the form of US dollars or government bonds.