JP MORGAN CHASE/HSBC
Together, JP Morgan Chase and HSBC controlled so much of the silver market - over 85 percent - that it became easy to manipulate. They came under scrutiny in 2008 for allegedly earning billions through tactics like manufacturing rumors that silver prices would depress, so they could cash in when they did. The suit was dismissed in 2013.
For proof of how easy it is to manipulate the price of penny stocks, look no further than Jonathan Lebed, who was only 15 when the SEC prosecuted him for the practice in 2000. From his bedroom in New Jersey, Lebed made hundreds of thousands posting to online chat rooms encouraging strangers to buy stocks he already owned, driving up their price. In 2001, he and the SEC negotiated an out-of-court settlement by which he paid $285,000 and admitted no wrongdoing.