Stock manipulation is a practice whereby owners of a company or others such as brokerage firms or investment companies take actions to increase or decrease the value of that stock, solely so they can buy or sell shares at a profit. It is typically illegal and widely considered to be unethical. For example, the CEO of a company may give a false, gloomy prediction of the company's future earnings in order to drive prices down so that he can purchase stock at a reduced price.
