Dado Ruvic/Reuters Bitcoin slumped as much as 18%, to $45,000, on Tuesday before slightly paring losses.Other cryptocurrencies such as ether and XRP also plunged as cash fled the market.Investors have second-guessed the recent market rally, with tech stocks also tumbling.Sign up here for our daily newsletter, 10 Things Before the Opening Bell.Bitcoin plunged as much as 18%, to $45,000, on Tuesday before slightly paring some losses as sky-high cryptocurrency valuations unnerved investors.The cryptocurrency traded 13% lower, at $47,608.24, as of 11:45 p.m.