The very worst thing one could do is to short a stock on the way up, and up fast. A very few may be able to catch the top but most likely you will be wiped out badly before the peak is reached. Just do the math that's investment 101 easy.
Better way to short is to sell way out of money calls. Collected 20 bucks for Sept. 195's. I am also trying to sell some 100 puts as well. High volatility is the same reason the big money boys are playing in this sand box.