I am fairly new to options and I am trying to understand how an assignment to part of a spread would affect p/l. Using a short put butterfly as an example using GOOG 500 2.75/-1 510 7.55/+2 520 15.60/-1 total credit is 3.25 or $325 stock is at 505.35 now lets say a few days later the 520 put is assigned early. 500 8.25 510 18.00 520 27.95 the trade at this point is up $305 and the stock is at 492.01. Now lets say that I were to exercise the 510 puts to cover the 520 assignment and decide to exit the rest of the trade (sell the remaining 510 long and buy back the 500). I calculated the trade to be down $505, is this correct?