This Bloomberg Opinion piece does a nice job of explaining the craziness that has happened in that stock over the last couple of days.

It gets a little in-the-weeds when he starts talking about the options strategies and their impacts, but I found the footnotes helpful.

The technical story is just that these two factors—a short squeeze and a gamma trap, if you like—combined to push the stock up rapidly on Friday. Something started the ball rolling—the stock went up for some fundamental or emotional or whatever reason—and then the stock going up forced short sellers and options market makers to buy stock, which caused it to go up more, which caused them to buy more, etc.

Here is a YOLO story, a story of utter nihilism. You know this story. This story is perhaps best told with a series of rocket emojis, but let’s try words instead. The people on the WallStreetBets subreddit sometimes all get into a stock at once. This is fun, a nice social outing in an age of social distancing, a risky but potentially lucrative collective entertainment. Recently they decided to do GameStop. Because, I don’t know, they’re gamers, or because it’s a little comical to pump the stock of a chain of mall video-game stores during a pandemic, or because a lot of professional investors are short GameStop and they thought it’d be funny to mess with them. Or, especially, because their friends on Reddit were buying GameStop and they figured they’d join in the fun. Or all of those things in different combinations. Take one person who’s long for fundamental reasons, add 100 people who are long for personal-amusement reasons like “lol gaming” or “let’s mess with the shorts,” and then add thousands more who are long because they see everyone else long, and the stock moves