Based on data from 3 February 2012 to 24 July 2012, an estimated $15 million in transactions were made annually on Silk Road.[72][73] Twelve months later, Nicolas Christin, the study's author, said in an interview that a major increase in volume to "somewhere between $30 million and $45 million" would not surprise him.[74] Buyers and sellers conducted all transactions with bitcoins (BTC), a cryptocurrency that provides a certain degree of anonymity.[75] Silk Road held buyers' bitcoins in escrow until the order had been received and a hedging mechanism allowed sellers to opt for the value of bitcoins held in escrow to be fixed to their value in US$ at the time of the sale to mitigate against Bitcoin's volatility. Any changes in the price of bitcoins during transit were covered by Dread Pirate Roberts.[76]