APPLICATIONS OF OPTION PRICING THEORY TO EQUITY VALUATION
			Application of option pricing models to valuation
A few caveats on applying option pricing models 
		
		1. The underlying asset is not traded
2. The price of the asset follows a continuous process
3. The variance is known and does not change over the life of the option
4. Exercise is instantaneous
I. Valuing Equity as an option
The General Framework
Equity as a call option
Payoff to equity on liquidation
= V - D if V > D 
		
		= 0 if V 
		
		where, 
		
		V = Value of the firm 
		
		D = Face Value of the outstanding debt and other external claims
Payoff on exercise = S - K if S > K 
		
		= 0 if S 
		
Payoff Diagram for Equity as a Call Option

Illustration 3: Application to valuation: A simple example
Model Parameters
The parameters of equity as a call option are as follows: 
		
		Value of the underlying asset = S = Value of the firm = $ 100
		million 
		
		Exercise price = K = Face Value of outstanding debt = $ 80 million
		
		
		Life of the option = t = Life of zero-coupon debt = 10 years 
		
		Variance in the value of the underlying asset = s2 = Variance in firm value = 0.16 
		
		Riskless rate = r = Treasury bond rate corresponding to option
		life = 10% 
		
Valuing Equity as a Call Option
Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.5994 N(d1) = 0.9451 
		
		d2 = 0.3345 N(d2) = 0.6310 
		
Value of the call = 100 (0.9451) - 80 exp(-0.10)(10) (0.6310)
			= $75.94 million
			
Value of the outstanding debt = $100 - $75.94 = $24.06 million
			
Interest rate on debt = ($ 80 / $24.06)1/10 -1 = 12.77%
			Implications of viewing equity as a call option
A. Valuing equity in a troubled firm
Illustration 4 : Value of a troubled firm
The parameters of equity as a call option are as follows: 
		
		Value of the underlying asset = S = Value of the firm = $ 50 million
		
		
		Exercise price = K = Face Value of outstanding debt = $ 80 million
		
		
		Life of the option = t = Life of zero-coupon debt = 10 years 
		
		Variance in the value of the underlying asset = s2 = Variance in firm value = 0.16 
		
		Riskless rate = r = Treasury bond rate corresponding to option
		life = 10% 
		
Valuing Equity in a Troubled Firm
Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.0515 N(d1) = 0.8534 
		
		d2 = -0.2135 N(d2) = 0.4155 
		
B. The Conflict between bondholders and stockholders
Illustration 5: Effect on value of the conflict between stockholders and bondholders
Value of Equity = $75.94 million 
		
		Value of Debt = $24.06 million 
		
		Value of Firm == $100 million
Valuing Equity after the Project
Value of the underlying asset = S = Value of the firm = $ 100
		million - $2 million = $ 98 million (The value of the firm is
		lowered because of the negative net present value project) 
		
		Exercise price = K = Face Value of outstanding debt = $ 80 million 
		
		Life of the option = t = Life of zero-coupon debt = 10 years 
		
		Variance in the value of the underlying asset = s2 = Variance in firm value = 0.25 
		
		Riskless rate = r = Treasury bond rate corresponding to option
		life = 10% 
		
		Based upon these inputs, the Black-Scholes model provides the
		following value for the equity and debt in this firm. 
		
		Value of Equity = $77.71 
		
		Value of Debt = $20.29 
		
		Value of Firm = $98.00
Illustration 6: Effects on equity of a conglomerate merger 
		
		You are provided information on two firms, which operate in unrelated
		businesses and hope to merge. 
		
		Firm A Firm B 
		
		Value of the firm $100 million $ 150 million 
		
		Face Value of Debt $ 80 million $ 50 million (Zero-coupon debt)
		
		
		Maturity of debt 10 years 10 years 
		
		Std. Dev. in firm value 40 % 50 % 
		
		Correlation between firm 
		
		cashflows 0.4 
		
		The ten-year bond rate is 10%.
Variance in combined firm value = w12 s12 + w22 s22 + 2 w1 w2 r12 s1 s2 
		
		= (0.4)2 (0.16) + (0.6)2 (0.25) + 2 (0.4) (0.6) (0.4) (0.4) (0.5) 
		
		= 0.154 
		
Valuing the Combined Firm
The values of equity and debt in the individual firms and the
		combined firm can then be estimated using the option pricing model: 
		
		Firm A Firm B Combined firm 
		
		Value of equity in the firm $75.94 $134.47 $ 207.43 
		
		Value of debt in the firm $24.06 $ 15.53 $ 42.57 
		
		Value of the firm $100.00 $150.00 $ 250.00
Obtaining option pricing inputs - Some real world problems
The examples that have been used to illustrate the use of option
		pricing theory to value equity have made some simplifying assumptions.
		Among them are the following: 
		
		(1) There were only two claim holders in the firm - debt and equity.
		
		
		(2) There is only one issue of debt outstanding and it can be
		retired at face value. 
		
		(3) The debt has a zero coupon and no special features (convertibility,
		put clauses etc.) 
		
		(4) The value of the firm and the variance in that value can be
		estimated. 
		
Applicability in valuation
|  |  | 
| Value of the Firm | 
 | 
| Variance in Firm Value | 
 s2firm = we2 se2 + wd2 sd2 + 2 we wd red sesd 
 | 
| Maturity of the Debt | 
 | 
North America $ 400 million 
		
		Europe $ 500 million 
		
		South America $ 100 million
Maturity Face Value Coupon Duration 
		
		20 year debt $ 100 mil 11% 14.1 years 
		
		15 year debt $ 100 mil 12% 10.2 years 
		
		10 year debt $ 200 mil 12% 7.5 years 
		
		1 year debt $ 800 mil 12.5% 1 year
Valuing Equity in the Airline
Step 1: Estimate the value of the firm = Sum of the value of its
		assets = 400 + 500 + 100 = 1,000 million 
		
		Step 2: Estimate the average duration of the debt outstanding
		= (100/1200) * 14.1 + (100/1200) * 10.2 + (200/1200) * 7.5 + (800/1200)
		* 1 = 3.9417 years 
		
		Step 3: Estimate the face value of debt outstanding = 100 + 100
		+ 200 + 800 = 1,200 million 
		
		Step 4: Estimate the variance in the value of the firm = Weighted
		average of the variances in stock and bond prices. = 
		
		Variance of the firm = (E/(D+E))2 se2 + (D/(D+E))2 sd2 + 2 (E/(D+E)) (D/(D+E)) red sesd 
		
		= (.1)2 (.25)2 + (.9)2 (.10)2 + 2 (.1)(.9)(.3) (.25)(.10) = 0.010075 
		
		Step 5: Value equity as an option 
		
		d1 = 0.7671 N(d1) = 0.7784 
		
		d2 = 0.5678 N(d2) = 0.7148 
		
Value of the call = 1000 (0.7784) - 1200 exp(-0.08)(3.9417) (0.7148) = $ 152.63 million
Debt Type Face Value Duration 
		
		Short term Debt $ 865 mil 0.5 years 
		
		Bank Debt $ 480 mil 3.0 years 
		
		Senior Debt $ 832 mil 6.0 years 
		
		Senior Subordinated $ 823 mil 8.5 years 
		
		Total $ 3000 mil 4.62 years
		
		Cost of Capital in high growth period = 16.03% (0.2986) + 10%
		(1 - 0.36) (0.7014) = 9.27% 
		
		Cost of Capital in terminal period = 13.55% (0.50) + 8.50% (1
		- 0.36) (0.50) = 9.34%
|  |  |  |  |  |  |  |  |  |  |  | |
| Revenues |  |  |  |  |  |  |  |  |  |  |  | 
| - COGS |  |  |  |  |  |  |  |  |  |  |  | 
| - Depreciation |  |  |  |  |  |  |  |  |  |  |  | 
| EBIT |  |  |  |  |  |  |  |  |  |  |  | 
| - EBIT*t |  |  |  |  |  |  |  |  |  |  |  | 
| EBIT (1-t) |  |  |  |  |  |  |  |  |  |  |  | 
| + Depreciation |  |  |  |  |  |  |  |  |  |  |  | 
| -Capital Spending |  |  |  |  |  |  |  |  |  |  |  | 
| - Æ Wking Capital |  |  |  |  |  |  |  |  |  |  |  | 
| Free CF to Firm |  |  |  |  |  |  |  |  |  |  |  | 
The stock and bond price variance are first annualized: 
		
		Annualized variance in stock price = 0.0133 * 12 = 0.16 Standard
		deviation = 0.40 
		
		Annualized variance in bond price = 0.0012 * 12 = 0.0144 Standard
		deviation = 0.12 
		
		Annualized variance in firm value 
		
		= (0.30)2 (0.16) + (0.70)2 (0.0.0144) + 2 (0.3) (0.7)(0.25)(0.40)(0.12)=
		0.02637668
The parameters of equity as a call option are as follows: 
		
		Value of the underlying asset = S = Value of the firm = $ 2871
		million 
		
		Exercise price = K = Face Value of outstanding debt = $ 3000 million 
		
		Life of the option = t = Weighted average duration of debt = 4.62
		years 
		
		Variance in the value of the underlying asset = s2 = Variance in firm value = 0.0264 
		
		Riskless rate = r = Treasury bond rate corresponding to option
		life = 7% 
		
		Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 0.9910 N(d1) = 0.8391 
		
		d2 = 0.6419 N(d2) = 0.7391 
		
Value of the call = 2871 (0.8391) - 3000 exp(-0.07)(4.62) (0.7395) = $ 817 million
		
		Cablevision's equity was trading at $1100 million in March 1995. 
		
		II. Valuing Natural Resource Options/ Firms 
		
		The General Framework
Payoff on natural resource investment = V - X if V > X 
		
		= 0 if V
		
Payoff on a Natural Resource Investment
			
			Obtaining the inputs for valuing natural resource options
|  |  | 
| 1. Value of Available Reserves of the Resource | 
 | 
| 2. Cost of Developing Reserve (Strike Price) | 
 | 
| 3. Time to Expiration | 
 | 
| 4. Variance in value of underlying asset | 
 | 
| 5. Net Production Revenue (Dividend Yield) | 
 | 
| 6. Development Lag | 
 | 
Inputs for the Option Pricing Model
Value of the underlying asset = Present Value of expected gold
		sales (@ 50,000 ounces a year) = (50,000 * 350) * (1- (1.0320/1.1020))/(.10-.03)
		- (50,000*250)* (1- (1.0420/1.1020))/(.10-.04) = $ 42.40 million 
		
		Exercise price = PV of Cost of opening mine = $40 million 
		
		Variance in ln(gold price) = 0.04 
		
		Time to expiration on the option = 20 years 
		
		Riskless interest rate = 9% 
		
		Dividend Yield = Loss in production for each year of delay = 1
		/ 20 = 5% 
		
		(Note: It will take twenty years to empty the mine, and the firm
		owns the rights for twenty years. Every year of delay implies
		a loss of one year of production.) 
		
Valuing the Option
Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.4069 N(d1) = 0.9202 
		
		d2 = 0.5124 N(d2) = 0.6958 
		
		Call Value= 42.40 exp(-0.05)(20) (0.9202) -40 (exp(-0.09)(20)
		(0.6958)= $ 9.75 million 
		
		The value of the mine as an option is $ 9.75 million, in contrast
		to the static capital budgeting analysis which would have yielded
		a net present value of $ 2.40 million ($42.40 million - $ 40 million).
		The additional value accrues directly from the mine's option characteristics.
		
		
Illustration 10: Valuing an oil reserve
Inputs to the Black-Scholes Model
Given this information, the inputs to the Black-Scholes can be
		estimated as follows: 
		
		Current Value of the asset = S = Value of the developed reserve
		discounted back the length of the development lag at the dividend
		yield = $12 * 50 /(1.05)2 = $ 544.22 
		
		(If development is started today, the oil will not be available
		for sale until two years from now. The estimated opportunity cost
		of this delay is the lost production revenue over the delay period.
		Hence, the discounting of the reserve back at the dividend yield) 
		
		Exercise Price = Present Value of development cost = $12 * 50
		= $600 million 
		
		Time to expiration on the option = 20 years 
		
		Variance in the value of the underlying asset = 0.03 
		
		Riskless rate =8% 
		
		Dividend Yield = Net production revenue / Value of reserve = 5% 
		
Valuing the Option
Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.0359 N(d1) = 0.8498 
		
		d2 = 0.2613 N(d2) = 0.6030 
		
		Call Value= 544 .22 exp(-0.05)(20) (0.8498) -600 (exp(-0.08)(20)
		(0.6030)= $ 97.08 million 
		
		This oil reserve, though not viable at current prices, still is
		a valuable property because of its potential to create value if
		oil prices go up. 
		
		Extending the option pricing approach to value natural resource
		firms
Inputs to the Black-Scholes Model
Input to model Corresponding input for valuing natural resource
		firm 
		
		Value of underlying asset Value of cumulated estimated reserves
		of the resource owned by the firm, discounted back at the dividend
		yield for the development lag. 
		
		Exercise Price Estimated cumulated cost of developing estimated
		reserves 
		
		Time to expiration on option Average relinquishment period across
		all reserves owned by firm (if known) or estimate of when reserves
		will be exhausted, given current production rates. 
		
		Riskless rate Riskless rate corresponding to life of the option
		
		
		Variance in value of asset Variance in the price of the natural
		resource 
		
		Dividend yield Estimated annual net production revenue as percentage
		of value of the reserve. 
		
		Illustration 11: Valuing an oil company - Gulf Oil in 1984
Valuing the Option
Value of underlying asset = Value of estimated reserves discounted
		back for period of development lag= 3038 * ($ 22.38 - $7) / 1.052
		= $42,380.44 
		
		Exercise price = Estimated development cost of reserves = 3038
		* $10 = $30,380 million 
		
		Time to expiration = Average length of relinquishment option =
		12 years 
		
		Variance in value of asset = Variance in oil prices = 0.03 
		
		Riskless interest rate = 9% 
		
		Dividend yield = Net production revenue/ Value of developed reserves
		= 5% 
		
		Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.6548 N(d1) = 0.9510 
		
		d2 = 1.0548 N(d2) = 0.8542 
		
		Call Value= 42,380.44 exp(-0.05)(12) (0.9510) -30,380 (exp(-0.09)(12)
		(0.8542)= $ 13,306 million 
		
Valuing Gulf Oil
Value of already developed reserves = 915 (1 - 1.125-10)/.125
		= $5065.83 
		
		Adding the value of the developed and undeveloped reserves of
		Gulf Oil provides the value of the firm. 
		
		Value of undeveloped reserves = $ 13,306 million 
		
		Value of production in place = $ 5,066 million 
		
		Total value of firm = $ 18,372 million 
		
		Less Outstanding Debt = $ 9,900 million 
		
		Value of Equity = $ 8,472 million 
		
		Value per share = $ 8,472/165.3 = $51.25 
		
		This analysis would suggest that Gulf Oil was overvalued at $70
		per share. 
		
III. Valuing product patents as options
The General Framework
Payoff from owning a product patent = V - I if V> I 
		
		= 0 if V 
		
		 
 
		
		Obtaining the inputs for option valuation 
|  |  | 
| 1. Value of the Underlying Asset | 
 | 
| 2. Variance in value of underlying asset | 
 | 
| 3. Exercise Price on Option | 
 | 
| 4. Expiration of the Option | 
 | 
| 5. Dividend Yield | 
 
 | 
Valuing the Option
The inputs to the option pricing model are as follows: 
		
		Value of the underlying asset = Present value of inflows (current)
		= $1,000 million 
		
		Exercise price = Present value of cost of developing product =
		$1,500 million 
		
		Time to expiration = Life of the patent = 20 years 
		
		Variance in value of underlying asset = Variance in PV of inflows
		= 0.03 
		
		Riskless rate = 10% 
		
		Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.1548 N(d1) = 0.8759 
		
		d2 = 0.3802 N(d2) = 0.6481 
		
		Call Value= 1000 exp(-0.05)(20) (0.8759) -1500 (exp(-0.10)(20)
		(0.6481)= $ 190.66 million
Illustration 13: Valuing a firm with only product options
Inputs to the Option Pricing Model
The inputs to the option pricing model are as follows: 
		
		Value of underlying asset = Present value of expected cashflows
		= $ 500 million 
		
		Exercise price = Present value of cost of developing product for
		commercial use = $400 mil 
		
		Time to expiration on the option = Time to expiration on patent
		rights = 25 years 
		
		Variance in value of underlying asset = 0.20 
		
		Riskless rate = 7% 
		
		Dividend yield = Expected annual cashflow / PV of cash inflows
		= 4% 
		
		Based upon these inputs, the Black-Scholes model provides the
		following value for the call: 
		
		d1 = 1.5532 N(d1) = 0.9398 
		
		d2 = -0.6828 N(d2) = 0.2474 
		
		Call Value= 500 exp(-0.04)(25) (0.9398) - 400 (exp(-0.07)(25)
		(0.2474)= $ 155.66 million
Valuing Biogen
Value of Existing Products = $ 12.14
Present Value of Cash Flows from Introducing the Drug Now = S
		= $ 3.422 billion 
		
		Present Value of Cost of Developing Drug for Commercial Use =
		K = $ 2.875 billion 
		
		Patent Life = t = 17 years Riskless Rate = r = 6.7% (17-year T.Bond
		rate) 
		
		Variance in Expected Present Values =s2 = 0.224 (Industry average firm variance for bio-tech firms) 
		
		Expected Cost of Delay = y = 1/17 = 5.89% 
		
		d1 = 1.1362 N(d1) = 0.8720 
		
		d2 = -0.8512 N(d2) = 0.2076 
		
Call Value= 3,422 exp(-0.0589)(17) (0.8720) - 2,875 (exp(-0.067)(17) (0.2076)= $ 907 million
		
		Call Value per Share from Avonex = $ 907 million/35.5 million
		= $ 25.55 
		
		Biogen Value Per Share = Value of Existing Assets + Value of Patent
		= $ 12.14 + $ 25.55 = $ 37.69