A thread about GameStop:

Big hedge funds made big bets that GameStop’s stock was overvalued. The way these bets work is the hedge fund borrows shares of the stock and sells those borrowed shares.

When it comes time to give the borrowed shares back, they buy them on the market, hopefully at lower prices. For example, they might sell the borrowed share at $50, hoping to be able to buy the share back at $30, to make a $20 profit. This is called shorting.

The hedge funds were so sure that GameStop was going down, that GameStop was the most shorted stock on the market. 140% of the shares in existence were “borrowed.” Imagine Bob borrows from Jane who borrows from Sue who borrows from John.

Shorting is risky, but the hedge funds were so sure that they just didn’t even care. People on Reddit realized this and basically thought “what if we all just bought shares and refused to sell them when the hedge funds need to give their borrowed shares back.”

The price goes up, the hedge funds are forced to buy back the expensive shares and lose money. Except the hedge funds kept doubling down as the price rode up, expecting that it would eventually fall. The Redditors weren't scared off and with "diamond hands" refused to sell.