Cryptocurrencies popped to the top of recent ranges on Monday as short sellers bailed out in the wake of a strong week and while traders hoped a handful of positive comments from influential investors might signal a turnaround in fragile sentiment. Twitter boss Jack Dorsey also said last week that the digital currency is a "big part" of the social media firm's future and, on Sunday, London's City A.M. newspaper reported - citing an un-named "insider" - that Amazon is looking to accept bitcoin payments by year's end. "Over the last five trading sessions we've seen general near-term bullishness in the market, driven by key technicals, as well as recent positive comments," said Ryan Rabaglia, global head of trading at digital asset platform OSL.