Tomorrow, on January 17th, the first bitcoin futures will settle. The CBOE cash-settled contracts will settle based on the 4pm ET Gemini auction - which means they are as vulnerable to manipulation as the 4pm Gemini price itself. The 4pm auction has demonstrated relatively low volume in the past (an average of only 35 bitcoin during the first 10 days of January), raising near-term concerns.
On New Year's Day, just 0.0735 BTC was sold at auction for an approximate price of $985.50. Then, on January 8, 2018, the Gemini auction hosted a volume of 102 bitcoin, corresponding to an auction price of approximately $14,938 per bitcoin, and a total notional value of $1.52 million. Browsing Gemini's historical data, it's clear that the amount of bitcoin auctioned each day varies significantly. And, like the global bitcoin price, the auction price itself has been fairly volatile. However, there appears to be a small but persistent premium for bitcoin sold via auctions, as the "absolute difference" is typically a small positive percentage.