BTC's parabolic trendlines formed in 2014. These had been respected until the parabolic resistance was broken late November, amid announcements by CME and CBOE that futures trading would commence in early-mid December on their respective platforms. In anticipation of futures trading bringing institutional investment to the space, speculation drove the price of BTC up in linear fashion (and drove many altcoins to reach astronomical highs). BTC finally underwent a correction, as was widely expected, starting December 17 and now looks to be re-entering the envelope. The parabolic support line is strong as it has been consistently respected for 3 years. Next support found at the linear trend line.