 From January 2017 to September 2018, the amount of tethers outstanding grew from about $10 million to about $2.8 billion.In early 2018 Tether accounted for about 10% of the trading volume of bitcoin, but during the summer of 2018 it accounted for up to 80% of bitcoin volume.Research suggests that a price manipulation scheme involving tether accounted for about half of the price increase in bitcoin in late 2017.