February 24th, 2004, 5:05 am
Why is it a BIG problem in worst of modeling ? i don't understand the following statements. can u explain further ?>>The Underlying.>>Worst Of:>>This is a big modelling problem in my view. Really big!>>It is fine in a simple world but there are significant cross greek terms - primarily - d(delta)/d(Vol) which most models >>do not take into account.>> short your cash-future BASIS is highly volatility dependant.>>This is something that NOBODY prices in correctly.Also SKEW BIG PROBLEM, how to cater ?>>A napolean on most equities is a guess as you have to make an adjustment/estimate for the effect of skew. OK, in brief i am based in an emerging market , not highly developed place (like NY, LONDON where there are always liquidity). When I do my Monte Carlo model for pricing Worst OF, I only assume everything very very simple:SDE with contant coefficientno volatiltiy smileno skew.What will be the effect if i missed out all these stuffs ? ANyway, in an emering market, does all these advanced quant stuffs can apply ? (e.g. stochastic vol model)ANother issue concerns the hedging:AT the end of the day, the model only gives me the delta, gamma .. with respect to the underlying STOCKS.But the trader won't be so stupid to hedge in thsi way, probably they hedge dynamically by THE OPTIONS instead.So the models are all useless ?? (unless i can get the delta with respect to the OPTIONS , ie. the no. of optiosn to buy/sell). Am I wrong ???Last question, I played with my model and found the following strange phenomeon:WORST-OF-PUT DECREASE WHEN CORR. INCREASES WORST-OF-PUT INCREASE WHEN CORR. DECREASES WORST-OF-CALL INCREASE WHEN CORR. INCREASES WORST-OF-CALL DECREASE WHEN CORR. DECREASES BEST-OF-PUT INCREASE WHEN CORR. INCREASES BEST-OF-PUT DECREASE WHEN CORR. DECREASES BEST-OF-CALL DECREASE WHEN CORR. INCREASES BEST-OF-CALL INCREASE WHEN CORR. DECREASES can anybody explain NON-MATHEMATICALLY WHY ????- I remembered UBS (Before merge) played a lot with these stuffs and finally got burned.what are the HIDDEN RISKS to the investors ??? Somebody said that as corr. increase, the vol. actually decreases (in risk magazine) I don't understand ???Thank you buddy.