Fundstrat Global Advisors co-founder Tom Lee recently explained in Twitter that he believes the S&P 500 may be a major contributor to bitcoin price movements. He said: "This is an unpopular view: Bitcoin will not hit a new high until the S&P 500 hit a new high. BTC has been fluctuating within the range due to macroeconomic instability. Our bitcoin pain index ( BMI) illustrates this from the fall of 66 (now 50). Since 2009, the best year for Bitcoin is when the S&P 500 is up 15%."