Where it can come unstuck, is when the volume of borrowed shares...

Where it can come unstuck, is when the volume of borrowed shares is rather large. For example 450M odd shares are shorted about now, give or take, and when covering starts the volume of shares on the seller side may well dry up. Whilst buying back those 450M, the price may well rise from the $3.60 to well above $4.20. Especially given good news can bring more holders to the market to compete for the shares being bought back to be returned. A good example of what's happened in recent times much to the shorter's chagrin is GameStop. Short selling occurs for a variety of reasons, often to drive the price down, triggering stop losses of retail holders and to continue the same with deep pockets, only to scoop up undervalued shares and gain a substantial holding. DYOR