220.1 Option Basics Financial Option Call Option A contract that gives its owner the right (but not the obligation) to purchase or sell an asset at a fixed price as some future dateCall OptionA financial option that gives its owner the right to buy an asset
320.1 Option Basics (cont'd) Put Option Option Writer A financial option that gives its owner the right to sell an assetOption WriterThe seller of an option contract
4Understanding Option Contracts Exercising an OptionWhen a holder of an option enforces the agreement and buys or sells a share of stock at the agreed-upon priceStrike Price (Exercise Price)The price at which an option holder buys or sells a share of stock when the option is exercisedExpiration DateThe last date on which an option holder has the right to exercise the option
5Understanding Option Contracts (cont'd) American OptionOptions that allow their holders to exercise the option on any date up to, and including, the expiration dateEuropean OptionOptions that allow their holders to exercise the option only on the expiration dateNote: The names American and European have nothing to do with the location where the options are traded.
6Understanding Option Contracts (cont'd) The option buyer (holder)Holds the right to exercise the option and has a long position in the contractThe option seller (writer)Sells (or writes) the option and has a short position in the contractBecause the long side has the option to exercise, the short side has an obligation to fulfill the contract if it is exercised.The buyer pays the writer a premium.
7Interpreting Stock Option Quotations Stock options are traded on organized exchanges.By convention, all traded options expire on the Saturday following the third Friday of the month.Open InterestThe total number of contracts of a particular option that have been written
9Interpreting Stock Option Quotations (cont'd) At-the-moneyDescribes an option whose exercise price is equal to the current stock priceIn-the-moneyDescribes an option whose value if immediately exercised would be positiveOut-of-the-moneyDescribes an option whose value if immediately exercised would be negative
10Interpreting Stock Option Quotations (cont'd) Deep In-the-moneyDescribes an option that is in-the-money and for which the strike price and the stock price are very far apartDeep Out-of-the-moneyDescribes an option that is out-of–the-money and for which the strike price and the stock price are very far apart
13Alternative Example 20.1 Problem It is December 30, 2009 and you have decided to purchase 25 February put contracts on the DJIA with an exercise price of $106.13
14Alternative Example 20.1 Problem (continued) How much money will this purchase cost you?Is this option in-the-money or out-of-the- money?14
15Alternative Example 20.1 Solution The ask price is $3.30 per contract. The total cost is:25 × $3.30 × 100 = $8,250Since the strike price exceeds the current price, ($105.49) the put option is in-the-money.15
16Options on Other Financial Securities Although the most commonly traded options are on stocks, options on other financial assets, like the S&P 100 index, the S&P 500 index, the Dow Jones Industrial index, and the NYSE index, are also traded.
17Options on Other Financial Securities (cont'd) HedgeTo reduce risk by holding contracts or securities whose payoffs are negatively correlated with some risk exposureSpeculateWhen investors use contracts or securities to place a bet on the direction in which they believe the market is likely to move
1820.2 Option Payoffs at Expiration Long Position in an Option ContractThe value of a call option at expiration isWhere S is the stock price at expiration, K is the exercise price, C is the value of the call option, and max is the maximum of the two quantities in the parentheses
19Figure 20.1 Payoff of a Call Option with a Strike Price of $20 at Expiration
2020.2 Option Payoffs at Expiration (cont'd) Long Position in an Option ContractThe value of a put option at expiration isWhere S is the stock price at expiration, K is the exercise price, P is the value of the put option, and max is the maximum of the two quantities in the parentheses
23Alternative Example 20.2 Problem You own a put option on Dell stock with an exercise price of $17.50 that expires today. Plot the value of this option as a function of the stock price.
24Alternative Example 20.2 (cont'd) SolutionLet S be the stock price and P be the value of the put option. The value of the option is P= max( S,0)
25Short Position in an Option Contract An investor that sells an option has an obligation.This investor takes the opposite side of the contract to the investor who bought the option. Thus the seller’s cash flows are the negative of the buyer’s cash flows.
26Figure 20.2 Short Position in a Call Option at Expiration
29Profits for Holding an Option to Expiration Although payouts on a long position in an option contract are never negative, the profit from purchasing an option and holding it to expiration could be negative because the payout at expiration might be less than the initial cost of the option.
30Figure 20.3 Profit from Holding a Call Option to Expiration
33Returns for Holding an Option to Expiration The maximum loss on a purchased call option is 100% (when the option expires worthless).Out-of-the money call options are more likely to expire worthless, but if the stock goes up sufficiently it will also have a much higher return than an in-the-money call option.Call options have more extreme returns than the stock itself.
34Returns for Holding an Option to Expiration (cont'd) The maximum loss on a purchased put option is 100% (when the option expires worthless).Put options will have higher returns in states with low stock prices.Put options are generally not held as an investment, but rather as insurance to hedge other risk in a portfolio.
35Figure 20.4 Option Returns from Purchasing an Option and Holding It to Expiration (a) The return on the expiration date from purchasing one of the August call options in Table 20.1 on July 8, 2009, and holding the position until the expiration date; (b) the same return for the August put options in the table.
36Combinations of Options StraddleA portfolio that is long a call option and a put option on the same stock with the same exercise date and strike priceThis strategy may be used if investors expect the stock to be very volatile and move up or down a large amount, but do not necessarily have a view on which direction the stock will move.
38Combinations of Options (cont'd) StrangleA portfolio that is long a call option and a put option on the same stock with the same exercise date but the strike price on the call exceeds the strike price on the put
41Combinations of Options (cont'd) Butterfly SpreadA portfolio that is long two call options with differing strike prices, and short two call options with a strike price equal to the average strike price of the first two callsWhile a straddle strategy makes money when the stock and strike prices are far apart, a butterfly spread makes money when the stock and strike prices are close.
43Combinations of Options (cont'd) Protective PutA long position in a put held on a stock you already ownPortfolio InsuranceA protective put written on a portfolio rather than a single stock. When the put does not itself trade, it is synthetically created by constructing a replicating portfolio
44Combinations of Options (cont'd) Portfolio insurance can also be achieved by purchasing a bond and a call option.
45Figure 20.7 Portfolio Insurance The plots show two different ways to insure against the possibility of the price of Amazon stock falling below $45. The orange line in (a) indicates the value on the expiration date of a position that is long one share of Amazon stock and one European put option with a strike of $45 (the blue dashed line is the payoff of the stock itself). The orange line in (b) shows the value on the expiration date of a position that is long a zero-coupon riskfree bond with a face value of $45 and a European call option on Amazon with a strike price of $45 (the green dashed line is the bond payoff).
4620.3 Put-Call ParityConsider the two different ways to construct portfolio insurance discussed above.Purchase the stock and a putPurchase a bond and a callBecause both positions provide exactly the same payoff, the Law of One Price requires that they must have the same price.
4720.3 Put-Call Parity (cont'd) Therefore,Where K is the strike price of the option (the price you want to ensure that the stock will not drop below), C is the call price, P is the put price, and S is the stock price
4820.3 Put-Call Parity (cont'd) Rearranging the terms gives an expression for the price of a European call option for a non-dividend-paying stock.This relationship between the value of the stock, the bond, and call and put options is known as put-call parity.
51Alternative Example 20.6 Problem Assume: You want to buy a one-year call option and put option on Dell.The strike price for each is $15.The current price per share of Dell is $14.79.The risk-free rate is 2.5%.The price of each call is $2.23Using put-call parity, what should be the price of each put?51
52Alternative Example 20.6SolutionPut-Call Parity states:52
5320.3 Put-Call Parity (cont'd) If the stock pays a dividend, put-call parity becomes
5420.4 Factors Affecting Option Prices Strike Price and Stock PriceThe value of a call option increases (decreases) as the strike price decreases (increases), all other things held constant.The value of a put option increases (decreases) as the strike price increases (decreases), all other things held constant.
5520.4 Factors Affecting Option Prices (cont'd) Strike Price and Stock PriceThe value of a call option increases (decreases) as the stock price increases (decreases), all other things held constant.The value of a put option increases (decreases) as the stock price decreases (increases), all other things held constant.
56Arbitrage Bounds on Option Prices An American option cannot be worth less than its European counterpart.A put option cannot be worth more than its strike price.A call option cannot be worth more than the stock itself.
57Arbitrage Bounds on Option Prices (cont'd) Intrinsic ValueThe amount by which an option is in-the-money, or zero if the option is out-of-the-moneyAn American option cannot be worth less than its intrinsic value
58Arbitrage Bounds on Option Prices (cont'd) Time ValueThe difference between an option’s price and its intrinsic valueAn American option cannot have a negative time value.
59Option Prices and the Exercise Date For American options, the longer the time to the exercise date, the more valuable the optionAn American option with a later exercise date cannot be worth less than an otherwise identical American option with an earlier exercise date.However, a European option with a later exercise date can be worth less than an otherwise identical European option with an earlier exercise date
6020.6 Options and Corporate Finance Equity as a Call OptionA share of stock can be thought of as a call option on the assets of the firm with a strike price equal to the value of debt outstanding.If the firm’s value does not exceed the value of debt outstanding at the end of the period, the firm must declare bankruptcy and the equity holders receive nothing.If the value exceeds the value of debt outstanding, the equity holders get whatever is left once the debt has been repaid.
62Debt as an Option Portfolio Debt holders can be viewed as owners of the firm having sold a call option with a strike price equal to the required debt payment.If the value of the firm exceeds the required debt payment, the call will be exercised; the debt holders will therefore receive the strike price and give up the firm.If the value of the firm does not exceed the required debt payment, the call will be worthless, the firm will declare bankruptcy, and the debt holders will be entitled to the firm’s assets.
63Debt as an Option Portfolio (cont'd) Debt can also be viewed as a portfolio of riskless debt and a short position in a put option on the firm’s assets with a strike price equal to the required debt payment.When the firm’s assets are worth less than the required debt payment, the owner of the put option will exercise the option and receive the difference between the required debt payment and the firm’s asset value. This leaves the debt holder with just the assets of the firm.If the firm’s value is greater than the required debt payment, the debt holder only receives the required debt payment.
65Risk-free debt = Risky debt + Put option on firm assets Credit Default SwapsBy rearranging Equation 20.9, we can eliminate a bond’s credit risk by buying the very same put option to protect or insure it:Risk-free debt = Risky debt + Put option on firm assetsThis put option is called a credit default swap (or CDS).In a credit default swap, the buyer pays a premium to the seller and receives a payment from the seller to make up for the loss if the bond defaults.