I know of news manipulation, but i have not heard of exchange manipulation
If it was for volume, that is understandable, it is mostly done by exchanges who are new to the market, and would want to do everything possible to attract people to them, and for the news manipulation, that one is the major tool used by whales to pump the price of a particular coin, but these type of pump usually does not last, because in the end, people would have no use for the project product, which will make the value not to be sustained and eventually dumped, if not dumped first by the whale himself.