If you trade options, what method do you use to figure your current P/L? Especially for deciding when to cut your losses and close the trade out? For anyone trading spreads in the same month, any change in shape of the horizontal skew (between strikes) will affect your P/L, many times drastically. And this happens constantly throughout the day every few seconds. Secondly, supply/demand at certain strikes which temporarily drive up/drive down IV of the options at those strikes will also affect your P/L drastically if you've bought/sold those strikes in your spread. If you trade spreads which cross expiration months, it gets even more complicated with the intermonth skew. So how do you solve this problem, and at any given time, how do you figure your P/L for the purpose of closing a trade because it has hit your max loss amount? Thanks.