Long story short:
Shorts take out huge positions against GameStop for the last several years. This, along with their business suffering plus covid, drives the price down.
Retail traders like GME and start buying stock & LEAPS starting in 2019 and into 2020.
In December 2020, Ryan Cohen, founder of Chewy, purchases a 12% stake in GameStop. Shares rally on this news.
In early January, Cohen and two of his buddies from Chewy take seats on the board of directors. Shares rally on this news.
In the meantime, shorts increased their positions. It got to be 130% of the shares in the company were shorted. How does that happen? They borrow shares, sell them, borrow those shares, sell them... At some point, though, short sellers have to unwind their positions. They can only do that by purchasing shares on the open market. If there are lots of shares available to purchase, it's not a big deal. However, retail investors are buying every share they can get ahold of and the shorts have to pay a premium to get their shares back. In the meantime, the bankers for the shorts are forcing margin calls. The shorts can borrow more money to pay for their margin, but the interest on this is incredibly high.
It might be okay if the shorts only had the retail investors to deal with. They also have those who sell call options to deal with. If you sell a naked call, you have to start purchasing shares once the share price is above the strike price of the option you sold. The number of shares is proportional to the delta (how much the price of the option changes per dollar change of share price) of the option. So they purchase the shares. This in turn causes a gamma squeeze. Gamma is the change in delta for each dollar in price the share changes (the derivative of delta for those of you who took and remember Calculus I). Gamma squeeze forces the price even higher.
Blood is in the water. The largest shorting firm got an infusion of cash yesterday, but this does not mean the shorts will win or keep getting ammo. Quite the opposite. Hedge funds are getting in on this, sensing a chance to make some quick money and take out competitors.
I guess that wasn't short.