Trading above $58K on Sunday afternoon, Bitcoin (BTC-USD) this morning fell as low as $45K, and is currently changing hands at $46.5K. The action has been even uglier Ether (ETH-USD), which has sunk to the current $1,460 from above $2K on Sunday.Alt-coins like BNB (BNB-USD), Bitcoin Cash (BCH-USD), and Litecoin (LTC-USD) have fared far worse.There's no particular news other than the price had gotten way ahead of itself. Some negative comments from Treasury Sec. Janet Yellen yesterday morning were good for a couple of headlines, but it's not exactly like folks were expecting the longtime governing official to embrace Bitcoin.Way more interesting is that the U.S. central bank has hired a hodler to be its chief innovation officer. Sunayna Tuteja comes from TD Ameritrade, where she was that bank's head of digital assets.Stocks to watch: Microstrategy (MSTR), Riot Blockchain (RIOT), Marathon Patent (MARA), Grayscale Bitcoin Trust (GBTC), Osprey Bitcoin Trust