Does anyone has any suggestions, bibliography, papers, anything else related with vols surface interpol?RegardsBob

QuoteOriginally posted by: BobJeffersonDoes anyone has any suggestions, bibliography, papers, anything else related with vols surface interpol?RegardsBobIn Market Models Carol Alexander uses "cubic spline interpolation" from "Numerical Recipes in C", which obviously has an overview and some code. The latter that is, not the former.

yes.. spline interpolation is a method that is used in practice.

If you have a t least three reliable prices for an expiry, you can use the method explained in the paper at the following address. It has some more financial rationale than a spline interpolation.http://www.fabiomercurio.it/consistentfxsmile.pdf

Hi. The QuantLib open source software has some excellent volatility interpolation functions that can be implemented in excel.From memory, the function qlBlackVol will interpolate vols making sure that the surface is arbitrage freedownload the excel add-in package here

QuoteOriginally posted by: doublebarrier2000Hi. The QuantLib open source software has some excellent volatility interpolation functions that can be implemented in excel.From memory, the function qlBlackVol will interpolate vols making sure that the surface is arbitrage freedownload the excel add-in package hereoop's db, the link is a little unsaansitaave, I presume you meant this link

Here is a paper by Matthias Fengler:http://141.20.100.9/papers/pdf/SFB649DP2005-019.pdf

Be very careful with geometric interpolation methods (such as cubic spline) : they tend to generate weird implied distributions. Be careful also about what happens at the wings.

QuoteOriginally posted by: jschnazBe very careful with geometric interpolation methods (such as cubic spline) : they tend to generate weird implied distributions. Be careful also about what happens at the wings.care to elaborate ?

QuoteOriginally posted by: doreillyQuoteOriginally posted by: jschnazBe very careful with geometric interpolation methods (such as cubic spline) : they tend to generate weird implied distributions. Be careful also about what happens at the wings.care to elaborate ?Because the differentials of the curve are computed to fit the points and to make the curve differentiable, you can have kind of border effects when one point move: it will also change the shape of the curve on the adjacent points.So when the data is not very accurate you can have strange shapes (especially on a market move) which can also change very quickly (when the prices update). And if you try to extrapolate the curve after your last point, the shape is only dependant of what your algorithm found as differential to fit the last points and most implementations will just continue the curve in a kind of straight line. (meaning that you get huge variations when the last point move)

Well yes with any polynomial method you have a border effect in that the whole curve moves when a single point is shifted. This is not too bad though.But more important is that the distribution implied from the vol surface depends on the 2nd derivative of the option price with respect to the strike. Obviously this function incorporate your interpolation function, whose 2nd derviative therefore comes to play. Any local irregularity of this function gets magnified and this can result in very conunterintuitive, if not directly arbitrable, distribution curves. Even with a standard cubic spline applied to real mkt data for a very liquid asset you will find cases where your density function actually decreases at some points ...So you may actually be better off not interpolating at all ... and instead price vanillas off the same model you use for exotics (or maybe use it to generate more points on your smile grids).

Check out the paper by Nabil Kahale "An arbitrage-free interpolation of volatilities" published in 2004 Risk.

Eric Reiner, "The Characteristic Curve Approach to Arbitrage-Free Time Interpolation of Volatility", ICBI Global Derivatives Conference, 2004

>Eric Reiner, "The Characteristic Curve Approach to Arbitrage-Free Time Interpolation of Volatility", ICBI >Global Derivatives Conference, 2004does anyone have this presentation?

QuoteOriginally posted by: jrquant1Check out the paper by Nabil Kahale "An arbitrage-free interpolation of volatilities" published in 2004 Risk.anyone tried out this one? I just read through the introduction. It sounds very promising