According to the University of Texas the big surge in Bitcoin and other cryptocurrencies during late 2017 was created artificially using another cryptocurrency called Tether. The detailed report has been written and published by a finance professor-student duo of John Griffin and Amin Shams.
According to a repor by Digital Trends, the massive bull-run in cryptocurrencies during late 2017-early 2018 period was manipulated by Bitfinex, one of the largest unregulated digital currency exchanges on the market.