Bitcoin and ether ended Thursday in the red, but ether has surged more than 100% since mid-June.
Yu Chun Christopher Wong | S3studio | Getty Images
Bitcoin on Friday fell to its lowest level in more than three weeks, dipping below $22,000 amid a sudden crypto sell-off in early European trading.
Bitcoin briefly plunged from $22,738 to below $21,500 at 2:30 a.m. ET, according to CoinDesk data, before recovering slightly to just under $22,000…