Market Manipulation is a deliberate attempt to interfere with market integrity.
Market manipulation is the act of artificially inflating or deflating the price of a security or otherwise influencing the behavior of the market for personal gain. In cryptocurrency markets, manipulation can take many forms including pump and dump schemes, wash trading, spoofing, and more. This is a criminal offense in regulated markets, but in cryptocurrency markets, these tactics are rampant and hard to stop due to the lack of regulation and oversight.
A group of traders might inflate the price of a small-cap coin for their profit, and then sell it when other investors start buying it, causing its price to collapse and resulting in huge losses for those who bought at the high price.