This is oddly fascinating, even though I don't understand all of it. If I understand correctly:
A "short" is a bet that a stock price will fall: you promise to sell it on a certain date at a certain price, but you don't actually own the shares. On that day, the idea goes, you'll buy the shares at the lower price you expect and then turn around and fulfill your contract, pocketing the difference. I don't know if regular folks like you and me can do that, or if only investment funds and professional stock-market people can. There are some rules that are different for the big players and the little folks; I don't know if this is one of them.
So... some big Wall Street hedge funds (one often mentioned is Melvin Capital) placed vast quantities of shorts on a gaming-gear company that isn't doing well (GameStop). A bunch of people on Reddit observed this and said to Wall Street: hold my beer.
They bought the stock. Hundreds of thousands of people on Reddit bought the stock. At that scale, any individual participant doesn't have to buy a lot; you could play this game for $20 back when it started. And it's not like you can spend that $20 going out to a movie right now, so there was probably an untapped market of bored people looking for fun. Read more…