In early December, before the whole WallStreetBets mania started, GameStop had a market cap of $1.1 billion where 104% of the shares were sold short. Fellow Fool Dan Caplinger can tell you how it's possible to bet more than 100% of the company's total share count on a negative shorting strategy. GameStop's average daily trading volume stood at 8.4 million shares, which works out to an average dollar volume of roughly $133 million at the share prices of Dec. 1. Even then, that was a pretty heavy trading period because GameStop was the target of pressure from activist investors and other traders hoping for a dramatic turnaround in the video game retail business.