For Option lover, if you have a full time job and don't have time to watch the market,but you want to DT SPY, don't want to lost the chance to make money, and limit the risk if you are in wrong side of market, then you can usethe Advance order technique OCO.One cancel Other.
Take SPY put I just bot as a example. I bot July SPY 92 put @ 1.62
I don't want to watch it whole day, So I use OCO to set:
1. STOP Loss Sell SPY 92 put at $1.5 If I am wrong I lost $0.12
2. STOP win Sell SPY 92 put at 2.10 I don't want to hold over night, If I am right I make $0.48
You can use OCO to set two orders for your SPY put position.Of course only one order may fill. When anyone of above order be filled, it will automatically cancel the other order.So even you don't stay around, you do not need to wrong your order be double filled.Some broker firm provide this kind of Advanced order. Such as OptionXpress, IB etc.