It's been a wild year in the stock market. The rise of armchair traders on Reddit sent stocks like video game retailer GameStop and cinema company AMC soaring, burning hedge funds that were short.

The event helped fuel a narrative of David-esque retail investors taking on more sophisticated Goliath hedge funds. Caught in the crosshairs were investors who short — or borrow shares to sell on the market, wait for them to decline, then return them, pocketing the difference.