DOCSLIB.ORG

Option Implied Volatility Surface

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Option Implied Volatility Surface Implied Volatility Surface Liuren Wu Zicklin School of Business, Baruch College Options Markets (Hull chapter: 16) . Liuren Wu Implied Volatility Surface Options Markets 1 / 1 Implied volatility Recall the BSM formula: Ft;T 1 2 − −r(T −t) ln K 2 σ (T t) c(S; t; K; T ) = e [Ft;T N(d1) − KN(d2)] ; d1;2 = p σ T − t The BSM model has only one free parameter, the asset return volatility σ. Call and put option values increase monotonically with increasing σ under BSM. Given the contract specifications (K; T ) and the current market observations (St ; Ft ; r), the mapping between the option price and σ is a unique one-to-one mapping. The σ input into the BSM formula that generates the market observed option price is referred to as the implied volatility (IV). Practitioners often quote/monitor implied volatility for each option contract instead of the option invoice price. Liuren Wu Implied Volatility Surface Options Markets 2 / 1 The relation between option price and σ under BSM 45 50 K=80 K=80 40 K=100 45 K=100 K=120 K=120 35 40 t t 35 30 30 25 25 20 20 15 Put option value, p Call option value, c 15 10 10 5 5 0 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Volatility, σ Volatility, σ An option value has two components: I Intrinsic value: the value of the option if the underlying price does not move (or if the future price = the current forward). I Time value: the value generated from the underlying price movement. Since options give the holder only rights but no obligation, larger moves generate bigger opportunities but no extra risk | Higher volatility increases the option's time value. Liuren Wu Implied Volatility Surface Options Markets 3 / 1 Implied volatility versus σ If the real world behaved just like BSM, σ would be a constant. I In this BSM world, we could use one σ input to match market quotes on options at all days, all strikes, and all maturities. I Implied volatility is the same as the security's return volatility (standard deviation). In reality, the BSM assumptions are violated. With one σ input, the BSM model can only match one market quote at a specific date, strike, and maturity. I The IVs at different (t; K; T ) are usually different | direct evidence that the BSM assumptions do not match reality. I IV no longer has the meaning of return volatility, but is still closely related to volatility: F The IV for at-the-money option is very close to the \expected return volatility" over the horizon of the option maturity. F A particular weighted average of all IV 2 across different moneyness is very close to expected return variance over the horizon of the option maturity. I IV reflects (increases monotonically with) the time value of the option. Liuren Wu Implied Volatility Surface Options Markets 4 / 1 Implied volatility at (t; K; T ) At each date t, strike K, and expiry date T , there can be two European options: one is a call and the other is a put. The two options should generate the same implied volatility value to exclude arbitrage. I Recall put-call parity: c − p = er(T −t)(F − K). I The difference between the call and the put at the same (t; K; T ) is the forward value. I The forward value does not depend on (i) model assumptions, (ii) time value, or (iii) implied volatility. At each (t; K; T ), we can write the in-the-money option as the sum of the intrinsic value and the value of the out-of-the-money option: I If F > K, call is ITM with intrinsic value er(T −t)(F − K), put is OTM. Hence, c = er(T −t)(F − K) + p. I If F < K, put is ITM with intrinsic value er(T −t)(K − F ), call is OTM. Hence, p = c + er(T −t)(K − F ). I If F = K, both are ATM (forward), intrinsic value is zero for both options. Hence, c = p. Liuren Wu Implied Volatility Surface Options Markets 5 / 1 The information content of the implied volatility surface At each time t, we observe options across many strikes K and maturities τ = T − t. When we plot the implied volatility against strike and maturity, we obtain an implied volatility surface. If the BSM model assumptions hold in reality, the BSM model should be able to match all options with one σ input. I The implied volatilities are the same across all K and τ. I The surface is flat. We can use the shape of the implied volatility surface to determine what BSM assumptions are violated and how to build new models to account for these violations. I For the plots, do not use K, K − F , K=F or even ln K=F as the moneyness measure. Instead, use a standardized measure, such as ln K=pF ATMV τ , d2, d1, or delta. I Using standardized measure makes it easy to compare the figures across maturities and assets. Liuren Wu Implied Volatility Surface Options Markets 6 / 1 Implied volatility smiles & skews on a stock AMD: 17−Jan−2006 0.75 0.7 0.65 Short−term smile 0.6 0.55 Implied Volatility 0.5 Long−term skew 0.45 Maturities: 32 95 186 368 732 0.4 −3 −2.5 −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 Moneyness= ln(K/F ) σ√τ . Liuren Wu Implied Volatility Surface Options Markets 7 / 1 Implied volatility skews on a stock index (SPX) SPX: 17−Jan−2006 0.22 0.2 0.18 More skews than smiles 0.16 0.14 Implied Volatility 0.12 0.1 Maturities: 32 60 151 242 333 704 0.08 −3 −2.5 −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 Moneyness= ln(K/F ) σ√τ . Liuren Wu Implied Volatility Surface Options Markets 8 / 1 Average implied volatility smiles on currencies JPYUSD GBPUSD 14 9.8 9.6 13.5 9.4 13 9.2 12.5 9 8.8 12 Average implied volatility Average implied volatility 8.6 11.5 8.4 11 8.2 10 20 30 40 50 60 70 80 90 10 20 30 40 50 60 70 80 90 Put delta Put delta Maturities: 1m (solid), 3m (dashed), 1y (dash-dotted) . Liuren Wu Implied Volatility Surface Options Markets 9 / 1 Return non-normalities and implied volatility smiles/skews BSM assumes that the security returns( (continuously) compounding) are ∼ − 1 2 2 normally distributed. ln ST =St N (µ 2 σ )τ; σ τ . I µ = r − q under risk-neutral probabilities. A smile implies that actual OTM option prices are more expensive than BSM model values. I ) The probability of reaching the tails of the distribution is higher than that from a normal distribution. I ) Fat tails, or (formally) leptokurtosis. A negative skew implies that option values at low strikes are more expensive than BSM model values. I ) The probability of downward movements is higher than that from a normal distribution. I ) Negative skewness in the distribution. Implied volatility smiles and skews indicate that the underlying security return distribution is not normally distributed (under the risk-neutral measure |We are talking about cross-sectional behaviors, not time series). Liuren Wu Implied Volatility Surface Options Markets 10 / 1 Quantifying the linkage ( ) Skew. Kurt. ln K=F IV (d) ≈ ATMV 1 + d + d 2 ; d = p 6 24 σ τ If we fit a quadratic function to the smile, the slope reflects the skewness of the underlying return distribution. The curvature measures the excess kurtosis of the distribution. A normal distribution has zero skewness (it is symmetric) and zero excess kurtosis. This equation is just an approximation, based on expansions of the normal density (Read \Accounting for Biases in Black-Scholes.") The currency option quotes: Risk reversals measure slope/skewness, butterfly spreads measure curvature/kurtosis. Check the VOLC function on Bloomberg. Liuren Wu Implied Volatility Surface Options Markets 11 / 1 Revisit the implied volatility smile graphics For single name stocks (AMD), the short-term return distribution is highly fat-tailed. The long-term distribution is highly negatively skewed. For stock indexes (SPX), the distributions are negatively skewed at both short and long horizons. For currency options, the average distribution has positive butterfly spreads (fat tails). Normal distribution assumption does not work well. Another assumption of BSM is that the return volatility (σ) is constant | Check the evidence in the next few pages. Liuren Wu Implied Volatility Surface Options Markets 12 / 1 Stochastic volatility on stock indexes SPX: Implied Volatility Level FTS: Implied Volatility Level 0.5 0.55 0.5 0.45 0.45 0.4 0.4 0.35 0.35 0.3 0.3 0.25 0.25 Implied Volatility Implied Volatility 0.2 0.2 0.15 0.15 0.1 0.1 0.05 96 97 98 99 00 01 02 03 96 97 98 99 00 01 02 03 At-the-money implied volatilities at fixed time-to-maturities from 1 month to 5 years. Liuren Wu Implied Volatility Surface Options Markets 13 / 1 Stochastic volatility on currencies JPYUSD GBPUSD 28 12 26 24 11 22 10 20 9 18 16 8 Implied volatility 14 Implied volatility 7 12 6 10 8 5 1997 1998 1999 2000 2001 2002 2003 2004 1997 1998 1999 2000 2001 2002 2003 2004 Three-month delta-neutral straddle implied volatility.
Load more

Recommended publications
  • MERTON JUMP-DIFFUSION MODEL VERSUS the BLACK and SCHOLES APPROACH for the LOG-RETURNS and VOLATILITY SMILE FITTING Nicola Gugole
    International Journal of Pure and Applied Mathematics Volume 109 No. 3 2016, 719-736 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu AP doi: 10.12732/ijpam.v109i3.19 ijpam.eu MERTON JUMP-DIFFUSION MODEL VERSUS THE BLACK AND SCHOLES APPROACH FOR THE LOG-RETURNS AND VOLATILITY SMILE FITTING Nicola Gugole Department of Computer Science University of Verona Strada le Grazie, 15-37134, Verona, ITALY Abstract: In the present paper we perform a comparison between the standard Black and Scholes model and the Merton jump-diffusion one, from the point of view of the study of the leptokurtic feature of log-returns and also concerning the volatility smile fitting. Provided results are obtained by calibrating on market data and by mean of numerical simulations which clearly show how the jump-diffusion model outperforms the classical geometric Brownian motion approach. AMS Subject Classification: 60H15, 60H35, 91B60, 91G20, 91G60 Key Words: Black and Scholes model, Merton model, stochastic differential equations, log-returns, volatility smile 1. Introduction In the early 1970’s the world of option pricing experienced a great contribu- tion given by the work of Fischer Black and Myron Scholes. They developed a new mathematical model to treat certain financial quantities publishing re- lated results in the article The Pricing of Options and Corporate Liabilities, see [1]. The latter work became soon a reference point in the financial scenario. Received: August 3, 2016 c 2016 Academic Publications, Ltd. Revised: September 16, 2016 url: www.acadpubl.eu Published: September 30, 2016 720 N. Gugole Nowadays, many traders still use the Black and Scholes (BS) model to price as well as to hedge various types of contingent claims.
    [Show full text]
  • The Equity Option Volatility Smile: an Implicit Finite-Difference Approach 5
    The equity option volatility smile: an implicit finite-difference approach 5 The equity option volatility smile: an implicit ®nite-dierence approach Leif B. G. Andersen and Rupert Brotherton-Ratcliffe This paper illustrates how to construct an unconditionally stable finite-difference lattice consistent with the equity option volatility smile. In particular, the paper shows how to extend the method of forward induction on Arrow±Debreu securities to generate local instantaneous volatilities in implicit and semi-implicit (Crank±Nicholson) lattices. The technique developed in the paper provides a highly accurate fit to the entire volatility smile and offers excellent convergence properties and high flexibility of asset- and time-space partitioning. Contrary to standard algorithms based on binomial trees, our approach is well suited to price options with discontinuous payouts (e.g. knock-out and barrier options) and does not suffer from problems arising from negative branch- ing probabilities. 1. INTRODUCTION The Black±Scholes option pricing formula (Black and Scholes 1973, Merton 1973) expresses the value of a European call option on a stock in terms of seven parameters: current time t, current stock price St, option maturity T, strike K, interest rate r, dividend rate , and volatility1 . As the Black±Scholes formula is based on an assumption of stock prices following geometric Brownian motion with constant process parameters, the parameters r, , and are all considered constants independent of the particular terms of the option contract. Of the seven parameters in the Black±Scholes formula, all but the volatility are, in principle, directly observable in the ®nancial market. The volatility can be estimated from historical data or, as is more common, by numerically inverting the Black±Scholes formula to back out the level of Ðthe implied volatilityÐthat is consistent with observed market prices of European options.
    [Show full text]
  • Approximation and Calibration of Short-Term
    APPROXIMATION AND CALIBRATION OF SHORT-TERM IMPLIED VOLATILITIES UNDER JUMP-DIFFUSION STOCHASTIC VOLATILITY Alexey MEDVEDEV and Olivier SCAILLETa 1 a HEC Genève and Swiss Finance Institute, Université de Genève, 102 Bd Carl Vogt, CH - 1211 Genève 4, Su- isse. [email protected], [email protected] Revised version: January 2006 Abstract We derive a closed-form asymptotic expansion formula for option implied volatility under a two-factor jump-diffusion stochastic volatility model when time-to-maturity is small. Based on numerical experiments we describe the range of time-to-maturity and moneyness for which the approximation is accurate. We further propose a simple calibration procedure of an arbitrary parametric model to short-term near-the-money implied volatilities. An important advantage of our approximation is that it is free of the unobserved spot volatility. Therefore, the model can be calibrated on option data pooled across different calendar dates in order to extract information from the dynamics of the implied volatility smile. An example of calibration to a sample of S&P500 option prices is provided. We find that jumps are significant. The evidence also supports an affine specification for the jump intensity and Constant-Elasticity-of-Variance for the dynamics of the return volatility. Key words: Option pricing, stochastic volatility, asymptotic approximation, jump-diffusion. JEL Classification: G12. 1 An early version of this paper has circulated under the title "A simple calibration procedure of stochastic volatility models with jumps by short term asymptotics". We would like to thank the Editor and the referee for constructive criticism and comments which have led to a substantial improvement over the previous version.
    [Show full text]
  • PAK Condensed Summary Quantitative Finance and Investment Advanced (QFIA) Exam Fall 2015 Edition
    PAK Condensed Summary Quantitative Finance and Investment Advanced (QFIA) Exam Fall 2015 Edition CDS Options Hedging Derivatives Embedded Options Interest Rate Models Performance Measurement Volatility Modeling Structured Finance Credit Risk Models Behavioral Finance Liquidity Risk Attribution PCA MBS QFIA Exam 2015 PAK Condensed Summary Ribonato-7 Ribonato-7 Empirical Facts about Smiles Fundamental and Derived Analysis The two potential strands of empirical analysis: 1. Fundamental analysis and 2. Derived Analysis In the fundamental analysis, it is recognized that the value of options and other derivatives contracts are derived from the dynamics of the underlying assets. The fundamental analysis is relevant to the plain vanilla options trader. The derived approach is of great interests to the complex derivatives trader. Not only the underlying assets but also other plain-vanilla options constitute the set of hedging instruments. In the derived approach, implied volatilities (or options prices) and the dynamics of the underlying assets are relevant. But mis-specification of the dynamics of the underlying asset is often considered to be a ‘second-order effect’. The complex trader usually engages in substantial vega and/or gamma hedging of the complex product using plain vanilla options. The delta exposure of the complex trade and of the hedging derivatives usually cancels out. Market Information About Smiles Direct Static Information The smile surface at time t is the function: : 퐼푚푝푙 2 휎푡 푅 → 푅 ( , ) ( , ) 퐼푚푝푙 푡 In principle, a better
    [Show full text]
  • The Empirical Robustness of FX Smile Construction Procedures
    Centre for Practiicall Quantiitatiive Fiinance CPQF Working Paper Series No. 20 FX Volatility Smile Construction Dimitri Reiswich and Uwe Wystup April 2010 Authors: Dimitri Reiswich Uwe Wystup PhD Student CPQF Professor of Quantitative Finance Frankfurt School of Finance & Management Frankfurt School of Finance & Management Frankfurt/Main Frankfurt/Main [email protected] [email protected] Publisher: Frankfurt School of Finance & Management Phone: +49 (0) 69 154 008-0 Fax: +49 (0) 69 154 008-728 Sonnemannstr. 9-11 D-60314 Frankfurt/M. Germany FX Volatility Smile Construction Dimitri Reiswich, Uwe Wystup Version 1: September, 8th 2009 Version 2: March, 20th 2010 Abstract The foreign exchange options market is one of the largest and most liquid OTC derivative markets in the world. Surprisingly, very little is known in the aca- demic literature about the construction of the most important object in this market: The implied volatility smile. The smile construction procedure and the volatility quoting mechanisms are FX specific and differ significantly from other markets. We give a detailed overview of these quoting mechanisms and introduce the resulting smile construction problem. Furthermore, we provide a new formula which can be used for an efficient and robust FX smile construction. Keywords: FX Quotations, FX Smile Construction, Risk Reversal, Butterfly, Stran- gle, Delta Conventions, Malz Formula Dimitri Reiswich Frankfurt School of Finance & Management, Centre for Practical Quantitative Finance, e-mail: [email protected] Uwe Wystup Frankfurt School of Finance & Management, Centre for Practical Quantitative Finance, e-mail: [email protected] 1 2 Dimitri Reiswich, Uwe Wystup 1 Delta– and ATM–Conventions in FX-Markets 1.1 Introduction It is common market practice to summarize the information of the vanilla options market in the volatility smile table which includes Black-Scholes implied volatili- ties for different maturities and moneyness levels.
    [Show full text]
  • Jump-Diffusion Models and Implied Volatility
    U.U.D.M. Project Report 2015:1 Jump-Diffusion Models and Implied Volatility Simon Wickstrom Examensarbete i matematik, 15 hp Handledare och examinator: Erik Ekström Januari 2015 Department of Mathematics Uppsala University Contents 1 Abstract 2 2 Introduction 3 2.1 Incomplete Markets . .3 2.2 Implied Volatility . .4 2.3 Volatility Smile and Skew . .4 3 Method 5 3.1 Valuing the Option . .6 3.2 Adding a Jump Process . .6 4 Results 7 4.1 Different stock price simulations for different K . 10 4.2 Numerical Problems . 11 4.3 Letting T ! 0 .......................... 11 5 Conclusion 16 6 References 17 7 Appendix 18 7.1 Underlying Function . 18 7.2 Simulation Program . 18 7.3 Simulation Program with different stock prices for different K 20 1 Chapter 1 Abstract The origin of this thesis came from a statement found in the book Financial Modelling With Jump Processes by Rama Cont and Peter Tankov. In the context of option pricing and volatilities, the introduction states: "Models with jumps, by contrast, not only lead to a variety of smile/ skew patterns but also propose a simple explanation in terms of market antici- pations: the presence of a skew is attributed to the fear of large negative jumps by market participants." This statement is written without any reference or proof and the object of this thesis was to examine whether it is true or not. The results from this thesis does confirm the statement. The statement has been tested by using a Monte-Carlo method in a the- oretical pricing model.
    [Show full text]
  • The Black-Scholes Formula and Volatility Smile
    University of Louisville ThinkIR: The University of Louisville's Institutional Repository Electronic Theses and Dissertations 5-2012 The Black-Scholes formula and volatility smile. Brian Michael Butler 1969- University of Louisville Follow this and additional works at: https://ir.library.louisville.edu/etd Recommended Citation Butler, Brian Michael 1969-, "The Black-Scholes formula and volatility smile." (2012). Electronic Theses and Dissertations. Paper 188. https://doi.org/10.18297/etd/188 This Master's Thesis is brought to you for free and open access by ThinkIR: The University of Louisville's Institutional Repository. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of ThinkIR: The University of Louisville's Institutional Repository. This title appears here courtesy of the author, who has retained all other copyrights. For more information, please contact [email protected]. THE BLACK-SCHOLES FORMULA AND VOLATILITY SMILE By Brian Michael Butler B.A., Humboldt State University, 1993 A Thesis Submitted to the Faculty of the College of Arts and Sciences of the University of Louisville in Partial Fulfillment of the Requirements for the Degree of Master of Arts Department of Mathematics University of Louisville Louisville, Kentucky May 2012 THE BLACK-SCHOLES FORMULA AND VOLATILITY SMILE By Brian Michael Butler B.A, Humboldt State University, 1993 A Thesis Approved on April 23, 2012 by the following Thesis Committee: Ewa Kubicka, Thesis Director Ryan Gill ii DEDICATION This thesis is dedicated to my wife Kelly Estep whose loving support and encouragement guided me onward in my education, and to our beautiful children, Aidan and Lily, who we hope to provide with the educational opportunities we received from our parents.
    [Show full text]
  • Foreign Exchange Implied Volatility Surface Copyright © Changwei
    Foreign Exchange Implied Volatility Surface Copyright © Changwei Xiong 2011 - 2021 January 19, 2011 last update: January 28, 2021 TABLE OF CONTENTS Table of Contents .........................................................................................................................................1 1. Trading Strategies of Vanilla Options ..................................................................................................3 1.1. Single Call and Put ........................................................................................................................3 1.2. Call Spread and Put Spread ...........................................................................................................3 1.3. Risk Reversal .................................................................................................................................4 1.4. Straddle and Strangle ....................................................................................................................4 1.5. Butterfly ........................................................................................................................................4 2. FX Option Quoting Convention...........................................................................................................5 2.1. Black-Scholes Formula .................................................................................................................5 2.2. Foreign-Domestic Symmetry ........................................................................................................7
    [Show full text]
  • Implied Trinomial Trees of the Volatility Smile
    Goldman Sachs Quantitative Strategies Research Notes February 1996 Implied Trinomial Trees of the Volatility Smile Emanuel Derman Iraj Kani Neil Chriss Goldman Sachs QUANTITATIVE STRATEGIES RESEARCH NOTES Copyright 1996 Goldman, Sachs & Co. All rights reserved. This material is for your private information, and we are not soliciting any action based upon it. This report is not to be construed as an offer to sell or the solicitation of an offer to buy any security in any jurisdiction where such an offer or solicitation would be illegal. Certain transactions, including those involving futures, options and high yield securities, give rise to substantial risk and are not suitable for all investors. Opinions expressed are our present opinions only. The material is based upon information that we consider reliable, but we do not represent that it is accurate or complete, and it should not be relied upon as such. We, our affiliates, or persons involved in the preparation or issuance of this material, may from time to time have long or short positions and buy or sell securities, futures or options identical with or related to those mentioned herein. This material has been issued by Goldman, Sachs & Co. and/or one of its affiliates and has been approved by Goldman Sachs International, regulated by The Securities and Futures Authority, in connection with its distribution in the United Kingdom and by Goldman Sachs Canada in connection with its distribution in Canada. This material is distributed in Hong Kong by Goldman Sachs (Asia) L.L.C., and in Japan by Goldman Sachs (Japan) Ltd. This material is not for distribution to private customers, as defined by the rules of The Securities and Futures Authority in the United Kingdom, and any investments including any convertible bonds or derivatives mentioned in this material will not be made available by us to any such private customer.
    [Show full text]
  • To Sigmoid-Based Functional Description of the Volatility Smile. Arxiv:1407.0256V3 [Q-Fin.MF] 8 Dec 2014
    To sigmoid-based functional description of the volatility smile. Andrey Itkin Polytechnic School of Engineering, New York University, 6 Metro Tech Center, RH 517E, Brooklyn NY 11201, USA December 9, 2014 Abstract We propose a new static parameterization of the implied volatility surface which is constructed by using polynomials of sigmoid functions combined with some other terms. This parameterization is flexible enough to fit market implied volatilities which demonstrate smile or skew. An arbitrage-free calibration algorithm is considered that constructs the implied volatility surface as a grid in the strike-expiration space and guarantees a lack of arbitrage at every node of this grid. We also demonstrate how to construct an arbitrage-free interpolation and extrapolation in time, as well as build a local volatility and implied pdf surfaces. Asymptotic behavior of this parameterization is discussed, as well as results on stability of the calibrated parameters are presented. Numerical examples show robustness of the proposed approach in building all these surfaces as well as demonstrate a better quality of the fit as compared with some known models. Keywords: volatility surface, static parametrization, arbitrage-free interpolation and extrapolation JEL classification: C6, C61, G17 arXiv:1407.0256v3 [q-fin.MF] 8 Dec 2014 1 Overview During last 15 years various parameterizations of the implied volatility (IV) surface were proposed in the literature to address few goals: a) given a set of market quotes for some options build an arbitrage-free local volatility (Dupire's) surface to further exploit it for calibration of a local stochastic volatility model; b) obtain volatilities for pricing OTC options and other derivatives with strikes and maturities other than that offered by the option exchanges; c) assess an adequacy of an option pricing model based on the shape of the IV 1 surface.
    [Show full text]
  • MANAGING SMILE RISK 1. Introduction. European Options Are
    MANAGING SMILE RISK PATRICK S. HAGAN¤, DEEP KUMARy ,ANDREWS.LESNIEWSKIz , AND DIANA E. WOODWARDx Abstract. Market smiles and skews are usually managed by using local volatility models alaDupire. We discover that the dynamics of the market smile predicted by local vol models is opposite of observed market behavior: when the price of the underlying decreases, local vol models predict that the smile shifts to higher prices; when the price increases, these models predict that the smile shifts to lower prices. Due to this contradiction between model and market, delta and vega hedges derived from the model can be unstable and may perform worse than naive Black-Scholes’ hedges. To eliminate this problem, we derive the SABR model, a stochastic volatility model in which the forward value satis…es ¯ dF^ =^aF^ dW1 d^a = º^adW2 and the forward F^ and volatility ^a are correlated: dW1dW2 = ½dt. We use singular perturbation techniques to obtain the prices of European options under the SABR model, and from these prices we obtain explicit, closed-form algebraic formulas for the implied volatility as functions of today’s forward price f = F^(0) and the strike K. These formulas immediately yield the market price, the market risks, including vanna and volga risks, and show that the SABR model captures the correct dynamics of the smile. We apply the SABR model to USD interest rate options, and …nd good agreement between the theoretical and observed smiles. Key words. smiles, skew, dynamic hedging, stochastic vols, volga, vanna 1. Introduction. European options are often priced and hedged using Black’s model, or, equivalently, the Black-Scholes model.
    [Show full text]
  • Implied Volatility Surface
    Implied Volatility Surface Liuren Wu Zicklin School of Business, Baruch College Options Markets Liuren Wu ( Baruch) Implied Volatility Surface Options Markets 1 / 25 Implied volatility Recall the BMS formula: Ft;T 1 2 r(T t) ln K ± 2 σ (T − t) c(S; t; K; T ) = e− − [Ft T N(d1) − KN(d2)] ; d1 2 = p ; ; σ T − t The BMS model has only one free parameter, the asset return volatility σ. Call and put option values increase monotonically with increasing σ under BMS. Given the contract specifications (K; T ) and the current market observations (St ; Ft ; r), the mapping between the option price and σ is a unique one-to-one mapping. The σ input into the BMS formula that generates the market observed option price (or sometimes a model-generated price) is referred to as the implied volatility (IV). Practitioners often quote/monitor implied volatility for each option contract instead of the option invoice price. Liuren Wu ( Baruch) Implied Volatility Surface Options Markets 2 / 25 The relation between option price and σ under BMS 45 50 K=80 K=80 40 K=100 45 K=100 K=120 K=120 35 40 t t 35 30 30 25 25 20 20 15 Put option value, p Call option value, c 15 10 10 5 5 0 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Volatility, σ Volatility, σ An option value has two components: I Intrinsic value: the value of the option if the underlying price does not move (or if the future price = the current forward).
    [Show full text]