Bitcoin sank to a more than one-week low, buffeted by investor skittishness ahead of a looming Federal Reserve interest-rate hike and amid harsher regulatory scrutiny of the cryptocurrency sector. The largest token dropped as much as 6.2pc on Tuesday and was trading at around $20,924 as of 10:02 a.m. in New York. The MVIS CryptoCompare Digital Assets 100 gauge shed more than 5pc, while recent high flyers Polygon and Ether was down about 10pc. Equity markets were mostly lower in the US and Europe. The retreat has put a dent in expectations for a sustained Bitcoin rebound and returned the token to a trading range between roughly $19,000 and $22,000. Risk appetite is generally on the back foot before an expected 75 basis-point Fed rate increase Wednesday, part of a tightening cycle that’s sapping liquidity.