In the last few days, the rather adventurous investors from the Reddit community Wallstreetbets even made it into the German news. The background was that this group, which now has 6 million members, tried to put a stop to the short-selling strategies of several hedge funds (especially Melvin Capital).
In this so-called short-selling, a hedge fund borrows the shares of a company and sells them (or derivatives on them). If the share price falls, the hedge fund can buy the shares back at a later date at a lower price and return them to the owner. Among the most "shorted" companies in recent weeks was Gamestop, an international chain of shops for video games, and the world's largest (??) cinema chain AMC. Both companies were not doing very well even before the Corona times. One could well describe both companies as typical "bankruptcy candidates", which is why companies like Melvin Capital are betting on their downfall on a grand scale.
What companies like Melvin Capital have not reckoned with, however, is an internet herd swarm that buys up the shares of the companies concerned on a grand scale, thus driving the prices to dizzying heights at the same time and no longer even selling them, but holding on to them. What should mean a total loss for the buyers of the shares at the latest in the case of a real bankruptcy of Gamestop or AMC, first causes sensitive 
billions of losses for the hedge funds, because they have to buy back the shares when their "bets" expire. And now at much higher prices. But if no one sells them the shares or they have even "shorted" more shares than they can buy back in the market, then their own buybacks also drive up the prices. This is called a short squeeze.
And this led to the fact that the price of the cinema chain AMC had quadrupled at times in the last few days and is still at dizzying levels. And this, in turn, has some circles cheering that the big-hearted WallsStreetBets investors have now effectively saved the cinema chain from its demise....
Coulda, shoulda... Cinema chain. However, anyone who knows anything about share trading knows that the price of shares once issued has no direct impact on the equity or revenue of the company itself. A high share price may help the company to borrow more cheaply, but the increase in the share price does not give AMC a cent more money in its coffers. And the owners cannot sell larger shares spontaneously, but have to announce such sales well in advance due to insider regulations.
And that is why AMC is by no means saved, but at best has landed in a breather. In order to really save AMC, other ideas must take hold...
;)