A surge day before earnings is never a reliable indication of what's to come; so many times I've seen a stock tank after a surge the day before, often because of less than expected or no guidance, or slightly missing estimates (look what just happened with AAPL). I sold 20% of my position at near cost today, because I don't feel entirely easy with lack of clarity on Apple-related production.
Yes ive seen big run-ups and then the tank many many times- Ive seen the reverse too but its almost impossible that they wont have a great 1//4. Ive already booked $6k in profits on this one and then bought back in 1100 shs-ah #$%$ somehow only have 900 now- I F'd up! My average this go around is 12.85