What The Heck Is A Dark Pool And Why Are People Trading In Them?

Last week, dozens of stock prices experienced violent swings because of strange trading activity that had people all over Wall Street scratching their heads. And while the investing public doesn’t know who (what firm) caused these price fluctuations, or why they engaged in the activity that had these stocks going nuts, we do know that, whoever they were, they were trading in a dark pool. Which prompts the question: What the heck is a dark pool and why are people trading in them? (Business Insider)