I'm endeavouring to work out the disparity in implied volatility of an identical strike 24h apart for a S&P500 option. My initial notion is to add up the alteration of delta, gamma, theta and the spot-volatility correlation vega + delta in the following manner: Price of the Option t0 -/+(dDelta)/(dSpot) -/+0.5 * Gamma * (dSpot)^2 -/+ Theta * dt -/+ dIV/dSpot * Vega -/+ dIV/dSpot * Delta ------------------------------------------- = Option Price t+1 adjusted ------------------------------------------- = Option Price in IV t+1 - Option Price in IV t0 ------------------------------------------- = Change in IV adjusted Am I making a mountain out of a molehill? Could a percentage rate for the difference in Delta be adequate?
Hello there, cheers once again I am grateful for your help. I completely slipped up and overlooked accounting for the IV for those 24h Your formula presumes a sticky strike behaviour, if I'm not off the mark? Otherwise, wouldn't we need to consider the spot vol correlation? On examining my formula, I might've double counted the change attributable to skew delta(?), but if we assume sticky delta (Index), doesn't the spot to implied volatility correlation need consideration(?)
sticky strike and sticky delta have nothing to do with the formula. THe formula is what your pnl is. The sticky behavior determines how the implied vol will move.
My objective is to find out whether the implied volatility of the (let's say) 4400 strike with a 30 Delta and 43IV has experienced a shift from yesterday to today. Perhaps all that's required of me is to: 40 IV t+1 - 43 IV t0 + 5 (negative) spot iv correlation | delta iv correlation ---------------------------------------------------------------- = +2 Adjusted IV change In this example the 4400 strike got bid up in t+1 eod
fixed strike shift is just the difference between yesterday and today. for sticky delta shift you have to compare the vol today to the delta/moneyness equivalent vol yesterday.