Crypto shares fall tracking weakness in bitcoin

** Shares of cryptocurrency and blockchain-related companies down premarket, hurt by weakness in bitcoin** Bitcoin , world's biggest cryptocurrency, falls ~2.3%, while Ether drops ~1.1%** Crypto exchange Coinbase Global down ~1.9%, U.S.-listed shares of blockchain farm operator Bitfarms Ltd down ~1.8%** Crypto miners Riot Platforms Inc , Hut 8 Mining and Marathon Digital down between ~2.5% and ~3.6%