Bitcoin records biggest intraday gain since Dec 2017, when the cryptocurrency hit a life high of nearly $20,000
Green says bitcoin could be back up because prices have bottomed out; expects bitcoin to hit $7,000 within months
"After being in bear territory there is a growing sense that bitcoin is back," Green says, adding Tuesday's dramatic jump is "likely to attract many investors who have been sitting on the sidelines"
Analysts also ascribe Tuesday's move to a major order, worth about $100 million, by an anonymous buyer that triggered computer-driven trading, spread across major crypto exchanges
Bitcoin surge triggers similar moves in other smaller currencies: Ethereum's ether and Ripple's XRP , respectively the second- and third-largest coins, up over 10 pct
Cryptocurrency-related stocks also up: currency miner Marathon Patent up 21 pct, blockchain company Riot 25 pct, DPW Holdings 19.6 pc.