Table of Contents
The Securities & Investment Institute
Title Page
Copyright Page
Dedication
PREFACE
Acknowledgements
Introduction
Chapter 1 - OPTIONS
1.1 EXAMPLES
1.2 AMERICAN VERSUS EUROPEAN OPTIONS
1.3 TERMINOLOGY
1.4 EARLY EXERCISE OF AMERICAN OPTIONS
1.5 PAYOFFS
1.6 PUT-CALL PARITY
Chapter 2 - THE BLACK – SCHOLES FORMULA
2.1 VOLATILITY AND THE BLACK-SCHOLES FORMULA
2.2 INTEREST RATE AND THE BLACK-SCHOLES FORMULA
2.3 PRICING AMERICAN OPTIONS
Chapter 3 - DIVIDENDS AND THEIR EFFECT ON OPTIONS
3.1 FORWARDS
3.2 PRICING OF STOCK OPTIONS INCLUDING DIVIDENDS
3.3 PRICING OPTIONS IN TERMS OF THE FORWARD
3.4 DIVIDEND RISK FOR OPTIONS
3.5 SYNTHETICS
Chapter 4 - IMPLIED VOLATILITY
4.1 EXAMPLE
4.2 STRATEGY AND IMPLIED VOLATILITY
Chapter 5 - DELTA
5.1 DELTA-HEDGING
5.2 THE MOST DIVIDEND-SENSITIVE OPTIONS
5.3 EXERCISE-READY AMERICAN CALLS ON DIVIDEND PAYING STOCKS
Chapter 6 - THREE OTHER GREEKS
6.1 GAMMA
6.2 THETA
6.3 VEGA
Chapter 7 - THE PROFIT OF OPTION TRADERS
7.1 DYNAMIC HEDGING OF A LONG CALL OPTION
7.2 DYNAMIC HEDGING OF A SHORT CALL OPTION
7.3 PROFIT FORMULA FOR DYNAMIC HEDGING
7.4 THE RELATIONSHIP BETWEEN DYNAMIC HEDGING AND θ
7.5 THE RELATIONSHIP BETWEEN DYNAMIC HEDGING AND θ WHEN THE INTEREST RATE IS ...
7.6 CONCLUSION
Chapter 8 - OPTION GREEKS IN PRACTICE
8.1 INTERACTION BETWEEN GAMMA AND VEGA
8.2 THE IMPORTANCE OF THE DIRECTION OF THE UNDERLYING SHARE TO THE OPTION GREEKS
8.3 PIN RISK FOR SHORT-DATED OPTIONS
8.4 THE RISKIEST OPTIONS TO GO SHORT
Chapter 9 - SKEW
9.1 WHAT IS SKEW?
9.2 REASONS FOR SKEW
9.3 REASONS FOR HIGHER VOLATILITIES IN FALLING MARKETS
Chapter 10 - SEVERAL OPTION STRATEGIES
10.1 CALL SPREAD
10.2 PUT SPREAD
10.3 COLLAR
10.4 STRADDLE
10.5 STRANGLE
Chapter 11 - DIFFERENT OPTION STRATEGIES AND WHY INVESTORS EXECUTE THEM
11.1 THE PORTFOLIO MANAGER’S APPROACH TO OPTIONS
11.2 OPTIONS AND CORPORATES WITH CROSS-HOLDINGS
11.3 OPTIONS IN THE EVENT OF A TAKEOVER
11.4 RISK REVERSALS FOR INSURANCE COMPANIES
11.5 PRE-PAID FORWARDS
11.6 EMPLOYEE INCENTIVE SCHEMES
11.7 SHARE BUY-BACKS
Chapter 12 - TWO EXOTIC OPTIONS
12.1 THE QUANTO OPTION
12.2 THE COMPOSITE OPTION
Chapter 13 - REPO
13.1 A REPO EXAMPLE
13.2 REPO IN CASE OF A TAKEOVER
13.3 REPO AND ITS EFFECT ON OPTIONS
13.4 TAKEOVER IN CASH AND ITS EFFECT ON THE FORWARD
Appendix A - PROBABILITY THAT AN OPTION EXPIRES IN THE MONEY
Appendix B - VARIANCE OF A COMPOSITE OPTION
BIBLIOGRAPHY
INDEX
The Securities & Investment Institute
Mission Statement:
To set standards of professional excellence and integrity for the investment and securities industry, providing qualifications and promoting the highest level of competence to our members, other individuals and firms.
The Securities and Investment Institute is the UK’s leading professional and membership body for practitioners in the securities and investment industry, with more than 16,000 members with an increasing number working outside the UK. It is also the major examining body for the industry, with a full range of qualifications aimed at people entering and working in it. More than 30,000 examinations are taken annually in more than 30 countries.
You can contact us through our website www.sii.org.uk
Our membership believes that keeping up to date is central to professional development. We are delighted to endorse the Wiley/SII publishing partnership and recommend this series of books to our members and all those who work in the industry.
As part of the SII CPD Scheme, reading relevant financial publications earns members of the Securities & Investment Institute the appropriate number of CPD hours under the Self-Directed learning category. For further information, please visitwww.sii.org.uk/cpdscheme
Ruth Martin Managing Director
Copyright © 2006 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777
Email (for orders and customer service enquiries):
[email protected] Visit our Home Page on www.wiley.com
All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley& Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to
[email protected], or faxed to (+44) 1243 770620
Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, trademarks or registered trademarks of their respective owners. The Publisher is not associated with any product or vendor mentioned in this book.
This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the Publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought.
Other Wiley Editorial Offices
John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA
Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA
Wiley-VCH Verlag GmbH, Boschstr. 12, D-69469 Weinheim, Germany
John Wiley & Sons Australia Ltd, 42 McDougall Street, Milton, Queensland 4064, Australia
John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore 129809
John Wiley & Sons Canada Ltd, 6045 Freemont Blvd, Mississauga, Ontario, Canada L5R 4J3
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN-13 978-0-470-02970-1 (PB) ISBN-10 0-470-02970-6 (PB)
Project management by Originator, Gt Yarmouth, Norfolk (typeset in 12/16pt Trump Mediaeval).
Printed and bound in Great Britain by T.J. International Ltd, Padstow, Cornwall.
This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production.
To Jan and Annelies
PREFACE
This book is appropriate for people who want to get a good overview of options in practice. It especially deals with hedging of options and how option traders earn money by doing so. To point out where the profit of option traders comes from, common terms in option theory will be explained, and it is shown how they relate to this profit. The use of mathematics is restricted to a minimum. However, since mathematics makes it possible to lift analyses to a non-superficial level, mathematics is used to clarify and generalize certain phenomena.
The aim of this book is to give both option practitioners as well as interested individuals the necessary tools to deal with options in practice. Throughout this book real life examples will illustrate why investors use option structures to satisfy their needs. Although understanding the contents of this book is a prerequisite for becoming a good option practitioner, a book can never produce a good trader. Ninety percent of a trader’s job is about dealing with severe losses and still being able to make the right decisions if such a loss occurs. The only way to become a good trader is to accept that, when helping clients to execute their option strategies, the trader will inevitably end up with positions where the risk reward is against him but the odds are in his favour. For that reason a one-off loss will almost always be larger than a one-off gain. But, if a trader executes many deals he should be able to make money on the small margin he collects on every deal even if he gets a few blow-ups.
ACKNOWLEDGEMENTS
This book is based on knowledge acquired during my work as a trader at Barclays Capital. Therefore, I would like to thank my colleagues at Barclays Capital who have been very helpful in teaching me the theory and practice of options. At Barclays Capital I would especially like to thank Faisal Khan and Thierry Lucas for giving me all the opportunities to succeed in mastering and practising option trading. I would also like to thank Thierry Lucas for his many suggestions and corrections when reviewing my work and Alex Boer for his mathematical insights. I would especially like to thank Karma Dajani for first giving me a great foundation in probability theory, then supervising my graduate dissertation in mathematics and, lastly, reviewing this book. Special thanks goes out to my father, Jan de Weert, for having been a motivating and helpful force in mastering mathematics throughout my life, and for checking the book very thoroughly and giving me many suggestions in rephrasing sentences and formulae more clearly.
INTRODUCTION
Over the years derivative securities have become increasingly important. Examples of these are options, futures, forwards and swaps. Although every derivative has its own purpose, they all have in common that their values depend on more basic variables like stocks and interest rates. This book is only concerned with options, but once the theory behind options is known, knowledge can easily be expanded to other derivatives.
This book has three objectives. The first is to introduce terms commonly used in option theory and explain their practical interpretation. The second is to show where option traders get their profit and how these commonly used terms relate to this profit. The last objective is to show why companies and investors use options to satisfy their financial needs.
Chapter 1
OPTIONS
Options on stocks were first traded on an organized exchange in 1973. That very same year Black and Scholes introduced their famous Black-Scholes formula. This formula gives the price of an option in terms of its parameters, like the underlying asset, time to maturity and interest rate. The formula and the variables it depends on will be discussed in more detail in the next chapters. Since 1973 option markets have grown rapidly, not only in volumes but also in the range of option products to be traded. Nowadays, options can be traded on many different exchanges throughout the world and on many different underlying assets. These underlying assets include stocks, stock indices, currencies and commodities.
There are two general kinds of options, the call option and the putoption. A call option gives the holder the right, but not the obligation, to buy the underlying asset for a pre-specified price and at a pre-specified date. A put option gives the holder the right, but not the obligation, to sell the underlying asset for a pre-specified price and at a pre-specified date. This pre-specified price is called the ‘strike price’; the date is known as the ’expiration date’, or ‘maturity’. The underlying asset in the definition of an option can be virtually anything, like potatoes, the weather, or stocks. Throughout this book the underlying asset will be taken to be a stock.
When the owner of a call option chooses to buy the stock, it is said that he exercises his option right. Of course, the same holds for the owner of a put option, only in this case the owner chooses to sell the stock, but it is still referred to as ‘exercising’ the option. If the option can only be exercised on the expiration date itself, the option is said to be a ‘European’ option. If it can be exercised at any time up to expiration, the option is an ‘American’ option. Although there are many other option types, the most important ones have already been covered: American call option, American put option, European call option and the European put option. The vast majority of the options that are traded on exchanges are American. However, it is useful to analyze European options, because properties of American options can very often be deduced from its European counterpart.
Before an example is given, it is worthwhile to look at the boldface sentence in the definition of an option. The holder of an option is not obligated to exercise the option. This means that at maturity the holder can decide not to do anything. This is exactly why it is called an ‘option’, the holder has a choice of doing something. Because of this choice, the largest loss an owner of an option can face is the price paid for the option.
1.1 EXAMPLES
Consider a holder of a European call option on the stock Royal Dutch/Shell with a strike price of $42. Suppose that the current stock price is $40, the expiration date is in 1 year and the option price is $5. Since the option is European, it can only be exercised on the expiration date. What are the possible payoffs for this option? If on the expiration date the stock price is less than $42, the holder of this option will clearly not exercise his option right. For if he did, he would buy the stock for $42 (exercising the option), and would only be able to sell the stock on the market for less than $42. So, the holder would incur a loss if he exercised his right, whereas nothing would happen if he did not exercise this right. In conclusion, if on the expiration date the stock price is less than $42, the holder does not exercise the option. In these circumstances the holder’s loss is the price paid for the option, in this case $5. If on the expiration date the stock price is between $42 and $47, the holder will exercise his option right. Suppose that the stock price on the expiration date is $45, then, by exercising his option right, he buys the stock for $42 and immediately sells this stock on the market for $45, making a profit of $3. However, taking into account that he paid $5 for the option, he still makes a loss of $2. It is clear that up to $47 the holder loses money on the option. If on the expiration date the stock price is more than $47, the holder will again exercise his option right. The difference between this case and the previous one is that the holder not only makes a profit by exercising his option right, he also makes an overall profit. Suppose that the stock price on the expiration date is $49, then his profit is $2, $7 from exercising the option and – $5 from the price paid for the option. Figure 1.1 shows the way in which the profit of the holder of a call option on Royal Dutch/Shell varies with the stock price at maturity.
This example points out that the profit of the holder of a call option increases as the stock price increases. Thus, the holder of a call option is speculating on an increasing stock price.
In contrast to a call option, the owner of a put option is hoping that the stock price will decrease. Consider a holder of a European put option on Unilever with a strike price of $50. Suppose that the current stock price is $50, the expiration date is in 6 months and the option price is $3. Again, because the put option is European it can only be exercised on the expiration date. What are the possible payoffs for the put option? Suppose that the stock price at maturity (expiration date) is more than $50. In this case the holder would not exercise his option right. Because he would have to buy the stock for more than $50, and, under the conditions of the put options, sell the same stock for $50. This would mean he would always incur a loss. So, if the stock price is more than $50, the holder does not exercise the option and faces a loss of $3, the price paid for the put option. If the stock price at maturity is between $50 and $47, the holder will exercise the option, but still make an overall loss. He will earn money by exercising the option, but it will not be enough to make up for the initial $3 paid for the option. If the stock price is less than $47 at maturity, the holder will exercise the option, and make an overall profit. He will make a profit of more than $3 by buying the stock on the market and immediately selling this stock for $50 under the conditions of the put option. Since the price paid for the put option was $3 he will also make an overall profit. Figure 1.2 shows the way in which the profit of the holder of the put option on Unilever varies with the stock price at maturity.
1.2 AMERICAN VERSUS EUROPEAN OPTIONS
If in above examples the options were American rather than European, the holders of the options would not have to wait until the expiration date before exercising the options. In the example of the put option on Unilever with strike price $50 this would mean that at any time during the 6 months, the holder is allowed to exercise the option. So, suppose that after 3 months the stock price is $40, the holder could decide to exercise his option right. By exercising he would make a profit of $7, $10 from exercising the option and – $3 from the price paid for the option.
Everything that can be done with a European option can be done with an American option, but the American option has the additional property that it can be exercised at any time up to the expiration date. This means that its price is always at least as much as its European counterpart.
Although most options that are traded on exchanges are American, this book mainly focuses on European options. Since American options are based on the same principles as European ones, and their properties can, very often, be easily derived from the European counterparts this is perfectly arguable. Throughout this book, an option is assumed to be European, unless specifically stated otherwise.
1.3 TERMINOLOGY
An option contract is an agreement between two parties. The buyer of the option is said to ‘have taken a long position’ in the option. The other party is said to have taken a ‘short position’ in the option, or is said to have ‘written’ the option. So, taking a long position essentially means ‘buying’ and taking a short position means ‘selling’. For that reason there are four general option positions:
1. A short position in a call option.
2. A short position in a put option.
3. A long position in a call option.
4. A long position in a put option.