Citron's Andrew Left shorts Grayscale Bitcoin Trust, buys bitcoin futures

Citron Research's Andrew Left said he's shorting Grayscale Bitcoin Trust ([[GBTC]] +4.7%) and buying bitcoin futures."If you're able to get the borrow and you hedge it out through the futures, you're making a free 70%-85%," Left said on Bloomberg Television.On Twitter, he also commented that 3,000% premium of Riot Blockchain ([[RIOT]] +5.8%) to net asset value will "historically look more ridic than 80%-100% premiums" GBTC traded to NAV in 2017.Riot should trade to NAV $2 (BTC+PP&E), he added in the post.Bitcoin gains 5% to $62.9K as Coinbase IPO buzz drives cryptocurrencies higher.