The figures for 4/30 were released - this was just people covering/selling to exit out the position instead of holding through earnings. Something like 8% of the shares short decided it would be better to get out. Something like 30% of the volume in those 2 weeks was people covering.
I have a market psychology question - assuming you don't have foreknowledge of the ER number - would you be more likely to cover your short from 4/15-4/30 if you're currently up + $.50/share or if you're only up $.15/share? More loss averse when up big or more gain seeking when up small?
Good question, but my instinct would be that your more likely to let your gains ride and the positive feedback on your thesis would strengthen your resolve in your position. That is assuming your looking for a substantial move, not just a short-term trader.