smilingsynch is right, your risk is double. Your new position is short the 140 and long the 120. Max risk is 140-120-credit=20-1/spread=19/spread, i.e. 1900x10=$19000 risk to make $1000. However, your roi stays the same, i.e. 1000/19000 x 100% ~ 5%. Best daddy's boy
Don't feel bad when I first read your post I couldn't see the mistake either. However, whenever I see a trade that looks that bad I always say "is there a way to profit by taking the other side". Generally if there is a mistake you'll find it trying to model the other side of the trade. Don