BlockBeats News, February 18th. According to Coinglass data, Coinbase's Bitcoin Premium Index has been at a negative premium for 34 consecutive days, currently at -0.0545%, exceeding the approximately 30 days of consecutive negative premium during the '1011 Crash' period.The Coinbase Bitcoin Premium Index is used to measure the difference between the Bitcoin price on Coinbase and the global market average price. A negative premium usually reflects selling pressure in the U.S. market, a decrease in investor risk appetite, a rise in market risk aversion, or capital outflows.