Goldman Sachs
Picture the scene: a conference room at Goldman Sachs where a manager and his underlings are having a meeting. The manager says "Boys, the price of oil is pretty high, what do you guys think if we sent a note to our "clients" stating we believe oil will drop by $20 in the near future and all the while we short sell oil and all our oil-based stocks". The underlings in unison "great idea, boss and when oil has dropped sufficiently, we send a note saying we believe price of oil will go up so we make money going long too". Meeting ends, everyone at Goldman Sachs makes a ton of money- small retail investor gets screwed.