I posted this in another thread as a crude example of how a ticker could see a short position over 100%.
This can be accomplished with a relatively small amount of shares in theory. If hedge fund A takes a 5% short position in a company, they sell those shares on the open market. Hedge fund B could then take an identical 5% short position with, in theory, the same shares that were shorted and sold by A. B then sells the same shares at market price. If this is done 25 times, you end up with a company having 125% of their shares being shorted when only 5% of their shares changed hands. This is an exaggerated example, but it shows how GME could see a short position of 138%.