Quote from akivak:
Okay, here is an example of butterfly:
Few weeks ago I sold RUT Jan 650/660 bear call spread for $1.25 credit. RUT was at 598. My plan was to sell OOM bull call spread on pullback. That pullback never came, and when RUT reached 640 few days ago, I was facing a dilemma. The 650/660 was worth around $2.5, and RUT was too close to the short strike. So I could cover the spread for $1.25 loss, or I could convert it to butterfly by selling 640/650 bull call spread for $6.5. I chose the second option.
I received total credit of $7.75. My maximum loss was fixed ($2.25) but I had a decent chance of at least some profit.
So today I took advantage of intraday moves to cover the butterfly. When RUT went down to 634, I covered the 650/660 call spread for $0.3. When RUT was at 644, I covered the 640/650 put spread for $5.1. My total profit: $2.35 on $2.25 margin (104%).
I think I was pretty lucky with this trade. I could hold and hope that RUT will go above 650 (in which case my profit would be 331%) but I never take settlement risk. No need to be greedy.