Estimate profit/loss of short-term SPX options with only underlying price (entry/exit) and delta

V

virw

If we know the underlying price (SPX index or SPY) at entry/exit of a short-term trade with SPX options, what is the best way to estimate the profit/loss of the trade? Underlying profit times delta works for small movement but for large movement it is not very accurate due to gamma. Assume the trade is very short term (< 30 minutes) so theta does not decay too much.
This is mainly used for back-testing.
 
The best way is to use an option pricing model in your backtester.

Otherwise, just lookup the pricing of a new strike price whose distance to the underlying price reflects the change in underlying values. Get the difference between the entry price and your lookup. What remains is inaccuracy due to vega.

That is part of trading "with the sheets".
 
You must log in or register to reply here.
Back
Top