Quote from jwcapital:
One way to play this: Buy the front month ATM put. Once the SPY has made its expected move, buy the SPY (underlying). This works well the week of expiration--which I am assuming is your time frame. If the SPY moves against you, you lose the PUT premium (for all intents and purposes). If the SPY moves the desired amount and keeps moving down after you buy the underlying, you have locked in a profit of four points minus the amount of the premium paid. If the SPY rebounds, then you make money on the long SPY position minus the premium paid. Otherwise, I would just short the SPY and set a stop loss.