What researchers have to say:
Researchers have come to a shocking conclusion that at least half of the rise in the prices of major cryptocurrencies and bitcoin may be due to a concentrated campaign of price manipulation. This came to light from recent papers published by John M Griffin and Amin Shams from the Department of Finance at the University of Texas.

To know more on https://www.globaltechinsights.com/ast-years-bitcoin-prices-were-mmanipulated/