I'm new to short selling stocks and wanted to know some of the technical order execution concerns people have faced. I understand the fundamental concerns of short selling (i.e., unlimited losses, etc). Some questions I have are: - Have you had issues with a brokerage having enough shares to borrow? - What quantity of shares do you have to be ordering for availability to become an issue? - Are you able to borrow the shares at the stated bid price? - Is order execution time significantly longer when shorting a stock compared to selling a long position? - Do you find some brokerages significantly better than others? - I'm developing an algorithmic trading script that short sells. When comparing back testing and paper trading results to actual execution, what additional discrepancies beyond what one finds with long positions should I expect? Thanks in advance!