If you talk about price manipulations, I have not seen this as often as volume manipulation.
However, I occasionally met with the strange behavior of the exchanges, when at the time of the pump of an coin, the large exchange unexpectedly left for unplanned technical work.
read news about coinmarketcap warned few exchange beause they don't give real data about trade volume and exhange liquidty.
many exchange are manipulate exchange data like i said