Thursday, May 16, 2013

The Volatility Surface: A Practitioner's Guide 1st edition, Jim Gatheral



The book is really sloppy in terms of the derivations and deduction of equations. For example, in page 7, the risk neutral SDE for volatility. The author publishes an error in his webpage for missing a term in the equation above the SDE, however, he doesn't say anything about how that will affect the result he derived later from that equation.

Another example is the equation (2.3) in pager 16, if you try to plug the numbers of alpha and beta as he mentioned to the equation (1.3)'you will find it impossible to get the equation (2.3). But when you look at his notes : [...], there are actually a lot of assumptions involved deriving the equation (2.3). I doubt whether he really check his maths in the book.

Last, it is good book if you want to get some general ideas of the volatility surfaces by reading just the texts and gliding through the deductions. But if you want to follow the maths and understand it completely, I don't think it is a good book.

This book of only about 160 pages packs a lot of punch. If you need to get to know anything about the volatility surface, this book will be of use. There are no elaborate derivations of formulae but everything needed is given. As a quant with many years of experience, Gatheral helped me in understanding the nitty gritty and nuances of volatility surfaces much better than before. He covers mostly everything from implied vol to local vol surfaces. It was very useful in my endeavours with variance swaps and generating volatility surfaces from traded data.

A good book for its wide view of all the topics linked to the volatility trading : stochastic volatility and jumps with a quite rare study of the impact of stochastic vol over the pricing of most commons exotic products like cliquets, lookback etc... The main problem of this book are :
1/ the incredible numbers of errors and typos in the proofs (typos for the two first chapters has been published by the author on the website of the Imperial College where Mr Gatheral has given lessons)
2/ the fact it's not so useful as the link between dividends and vol stochastic isn't treated at all.
3/ Most of the interesting theoretical exposee are clearly uncomplete and needs further investigation. But as the author try to do a wide tour of the subject in a rather limited number of pages, this is not surprising.
4/ This isn't explicit but this is of a weaker interest for stochastic volatility of underlyings other than Equities, index and funds...

So finally, it's a good tour on the subject but for a lot of subjects it look likes a summary. Others books are needed. mainly the Alan Lewis book for Fourier transform's methods of pricing, the Cont/tankov on the Jumps process (see my review of this one) and the Alireza Javaheri's one for a more deeper work on THE calibration problem of stochastic volatility.

Jim Gatheral has done everyone in quant fin a service by gathering and organizing his lectures, practical execution issues, and experience in this welcome volume, The Volatility Surface: A Practitioner's Guide. This is simply an excellent, clear work that defies the logic that good valuable books in finance don't get written because authors make more money elsewhere. Compare Gatheral with the execrable collection of disjointed papers with Jarrow's name slapped on it (Volatility, Jarrow, et al,1998). This is the book they were trying to write, but it took a practitioner who had his hands dirty and worked hard to try to explain what he was doing to write it.

Topics are rolled out extremely well, and Gatheral dives right in to where practitioners swim: volatility isn't a single data point, or a smile, but a surface and needs to be thought of that way. In explicating the volatility surface and the possible explanations for shapes Gatheral raises the level of conversation for everyone in the field: this is the way we must think of volatility now (until something better comes along, but given the curse of dimensionality my guess is we will be here for a very long time).

This is an excellent, necessary book. Full disclosure: I am not an expert in this field and only have friends who are (many of them are editorial and AMAZON reader reviewers cited here). This book assists me in having interesting and comprehensible conversations with them, but if there are any flaws they likely would escape me. So far, my friends who are experts all agree: thank you Jim Gatheral, excellent job. Very helpful and well worth the money.

I found this book by Jim Gatheral very useful from a practical standpoint. His insight for trading applications is remarkable. I reccommend this book to any derivative trader to read from cover to cover. Its filled w/ useful tips and concepts that will save you and your firm from the many pitfalls that arise in marketers trying to satisfy their clients at the house's expense.

Managers should make this required reading for all traders.

Too often we see authors unnecessarily overcomplicate mathematics. Jim Gatheral on the other hand does the reverse. By taking a difficult subject and presenting in a wonderfully concise and pedagogic style he shares with the reader his deep knowledge of volatility. Such an important financial quantity which still appears to invoke fear, Jim Gatheral uses his enviable blend of master practitioner and brilliant academic to combine both the real-world finance principles together with the underlying mathematics to demystify volatility.

The working is beautifully laid out, in a manner that is patient, friendly and approachable - and shows that quant finance need not look greek! This is the measure of a true genius!

As a teacher of mathematical finance, I have no hesitation in strongly recommending this book to students, researchers and practitioners in the field of derivatives.

The book is a great guide to understanding the different models used on Wall Street to capture the intricacies of modeling and pricing derivatives. The books focus of using models as a tool and NOT a solution is a great reminder to both traders and salespeople.

This summarized when the author describes the pricing of a digital cliquet.

"Those sellers using local Vol models will certainly value a digital cliquet at a lower price than sellers using stochastic volatility. Perversely then, those sellers using an inadequate model will almost certainly win the deal and end up short a portfolio of misvalued forward-starting digital options. OR even worse, a dealer could have an appropriate valuation approach but be pushed internally by the salespeople to match (mistaken) competitors' lower prices."

The Volatility Surface is an-ultra modern account of derivatives pricing and hedging. Indeed of the fifty-two bibliographical references a mere twenty were written before 1999. The book makes the case for option pricing models which incorporate randomness into stock price volatility (stochastic volatility) and jumps into stock price movements. By themselves these are not new models, but a coherent understanding of their relationship to the dynamics of the volatility surface and to derivatives valuation is new, and Gatheral does an admirable job of presenting a great deal of the most modern work in this area - including some of his own - in one place.

The topic is necessarily mathematical in nature and Gatheral spares the reader nothing of the full-on mathematical treatment; but he nevertheless manages to distill the essence of the most important mathematics into easily accessible, intuitive explanations that supplement the readers understanding. Thus this book should have broad appeal to practitioners of all levels, especially traders and those familiar with the basics of derivatives valuation. Gatheral succeeds in this vein so well, I believe, because he is a first-rate quant and a a long-time senior quant at Merril Lynch.

The book gives an excellent treatment of the relationship between stock price dynamics which actually explain option prices observed in the market and the necessity of studying the volatility surface to have a complete understanding of derivatives valuation. He does a great job of justifying the key models he reviews and then studies the implications for derivatives valuation.

As an expert practitioner, his choices reflect what is really out there in the market, so readers should pay attention. As a first rate quant, his mathematics and his grasp of the literature on option pricing will expose readers to the best of the best.

Of particular note is his last chapter on volatility instruments, in particular variance swaps, volatility swaps and options on volatility. This is an important market that was just getting started in the late 1990s but has burgeoned into one of the most active and important markets in equity derivatives. This chapter is a must for anyone interested in understanding the subtelties involved in understanding variance swap and volatility swap valuation, and is alone worth the cover price.

Very typical of the academic side of the study of the stock market and derivatives - making up unique notation, assuming simplifications (e.g., page 7, "... risk-neutral world."), and incomplete document editing (the Index listing for SDE is "See Stochastic differential equation" but there is no entry for Stochastic differential equation in the Index) - which casts doubt on the validity and applicability to a real-world trading environment.

Product Details :
Hardcover: 208 pages
Publisher: Wiley; 1 edition (August 28, 2006)
Language: English
ISBN-10: 0471792519
ISBN-13: 978-0471792512
Product Dimensions: 6.4 x 0.8 x 9.1 inches

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