Hi.It seems to me there's a mistake in the implied risk-neutral probability density function (in terms of implied vol.) formula page 295 of DERIVATIVES: the exponent should be -0.5*d2^2 and not d1^2 (otherwise in the case sigmaimp=const we do not come back to the usual lognormal probability density function).Now, a I have to admit I'm too lazy to redo the whole calculation... can somebody (Paul, are u there ?) confirm that it's the only glitch in the formula ?Cheers,Benny

You are correct. Let me get back to you on whether there are any other mistakes there.P

Paul, I guess it's just not possible to write a book with that many formulae, without having an error creeping in every here and there... (It happens to me whenever I write more than 3 pages!) Unless it is something like the 10th ed... One source of errors must be that there are so many different research articles in the field, and many times with slightly different definitions and choice of symbols, which should rather be translated to the defintions and choices of your book. Having said that I just wonder... Could you publish some errata lists on your books, perhaps on this site? I know there was one before on Derivatives. Actually, when I think about it, why not have a forum for this kind of lists for any finance book by any author? It could really be useful. Or perhaps that is one of the things the Student forum is for?