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Binnenlandse Francqui Leerstoel VUB 2004-2005 5. Options and Optimal Capital Structure. Professor André Farber Solvay Business School Université Libre de Bruxelles. Outline of presentation:. 1. Modigliani Miller 1958: review 2. Merton Model: review 3. Interest tax shield
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Binnenlandse Francqui Leerstoel VUB 2004-20055. Options and Optimal Capital Structure Professor André Farber Solvay Business School Université Libre de Bruxelles
Outline of presentation: • 1. Modigliani Miller 1958: review • 2. Merton Model: review • 3. Interest tax shield • 4. Bankruptcy costs and agency costs • 5. The tradeoff model: Leland VUB 05 Options and optimal capital structure
Modigliani Miller (1958) • Assume perfect capital markets: not taxes, no transaction costs • Proposition I: • The market value of any firm is independent of its capital structure: V = E+D = VU • Proposition II: • The weighted average cost of capital is independent of its capital structure WACC = rAsset • rAsset is the cost of capital of an all equity firm VUB 05 Options and optimal capital structure
Weighted average cost of capital V (=VU ) = E + D Value of equity rEquity Value of all-equity firm rAsset rDebt Value of debt WACC VUB 05 Options and optimal capital structure
Cost of equity • The equality WACC = rAsset can be written as: • Expected return on equity is an increasing function of leverage: rEquity 12.5% Additional cost due to leverage 11% WACC rA 5% rDebt D/E 0.25 VUB 05 Options and optimal capital structure
Why does rEquity increases with leverage? • Because leverage increases the risk of equity. • To see this, back to the portfolio with both debt and equity. • Beta of portfolio: Portfolio = Equity * XEquity + Debt * XDebt • But also: Portfolio = Asset • So: • or VUB 05 Options and optimal capital structure
The Beta-CAPM diagram Beta L βEquity U βAsset r rAsset rDebt=rf rEquity 0 D/E rEquity D/E rDebt WACC VUB 05 Options and optimal capital structure
Limited liability: equity viewed as a call option on the company. Merton (1974): Review D Market value of debt Risk-free debt - Put E Market value of equity Call option on the assets of the company Loss given default F Bankruptcy VMarket value of comany FFace value of debt VMarket value of comany FFace value of debt VUB 05 Options and optimal capital structure
Merton Model: example using binomial option pricing Data: Market Value of Unlevered Firm: 100,000 Risk-free rate per period: 5% Volatility: 40% Company issues 1-year zero-coupon Face value = 70,000 Proceeds used to pay dividend or to buy back shares Binomial option pricing: reviewUp and down factors: V = 149,182E = 79,182D = 70,000 Risk neutral probability : V = 100,000E = 34,854D = 65,146 V = 67,032E = 0D = 67,032 1-period valuation formula Cost of borrowing:y = 7.45% ∆t = 1 VUB 05 Options and optimal capital structure
Weighted Average Cost of Capital in Merton Model • (1) Start from WACC for unlevered company • As V does not change, WACC is unchanged • Assume that the CAPM holds WACC = rA= rf + (rM - rf)βA • Suppose: βA = 1 rM – rf = 6% WACC = 5%+6%× 1 = 11% • (2) Use WACC formula for levered company to find rE VUB 05 Options and optimal capital structure
Cost (beta) of equity • Remember : C = Deltacall× S - B • A call can is as portfolio of the underlying asset combined with borrowing B. • In Merton’s Model: E = DeltaEquity× V – B • The fraction invested in the underlying asset is X = (DeltaEquity× V) / E • The beta of this portfolio is X βasset In example: βA = 1 DeltaE = 0.96 V/E = 2.87 βE= 2.77 rE = 5% + 6%× 2.77 = 21.59% VUB 05 Options and optimal capital structure
Cost (beta) of debt • Remember : D = PV(FaceValue) – Put • Put = Deltaput× V + B (!! Deltaputis negative: Deltaput=Deltacall – 1) • So : D = PV(FaceValue) - Deltaput× V - B • Fraction invested in underlying asset is X = - Deltaput× V/D • βD = - βA Deltaput V/D In example: βA = 1 DeltaD = 0.04 V/D = 1.54 βD= 0.06 rD = 5% + 6% × 0.06 = 5.33% VUB 05 Options and optimal capital structure
Toward Black Scholes formulas Value Increase the number to time steps for a fixed maturity The probability distribution of the firm value at maturity is lognormal Bankruptcy Maturity Today Time VUB 05 Options and optimal capital structure
Corporate Tax Shield • Interest payments are tax deductible => tax shield • Tax shield = Interest payment × Corporate Tax Rate = (rD× D) × TC • rD: cost of new debt • D : market value of debt • Value of levered firm = Value if all-equity-financed + PV(Tax Shield) • PV(Tax Shield) - Assume permanent borrowing V=VU + TCD VUB 05 Options and optimal capital structure
Cost of equity calculation V = VU + TCD = E + D Value of equity rE rA Value of all-equity firm rD Value of debt Value of tax shield = TCD rD VUB 05 Options and optimal capital structure
Still a puzzle…. • If VTS >0, why not 100% debt? • Two counterbalancing forces: • cost of financial distress • As debt increases, probability of financial problem increases • The extreme case is bankruptcy. • Financial distress might be costly • agency costs • Conflicts of interest between shareholders and debtholders (more on this later in the Merton model) • The trade-off theory suggests that these forces leads to a debt ratio that maximizes firm value (more on this in the Leland model) VUB 05 Options and optimal capital structure
Risk shifting • The value of a call option is an increasing function of the value of the underlying asset • By increasing the risk, the stockholders might fool the existing bondholders by increasing the value of their stocks at the expense of the value of the bonds • Example (V = 100,000 – F = 60,000 – T = 2 years – r = 5%) Volatility Equity Debt 30% 46,626 53,374 40% 48,506 51,494 +1,880 -1,880 VUB 05 Options and optimal capital structure
Underinvestment • Levered company might decide not to undertake projects with positive NPV if financed with equity. • Example: F = 100,000, T = 5 years, r = 5%, σ = 30% V = 100,000 E = 35,958 D = 64,042 • Investment project: Investment 8,000 & NPV = 2,000 ∆V = I + NPV V = 110,000 E = 43,780 D = 66,220 ∆ V = 10,000 ∆E = 7,822 ∆D = 2,178 • Shareholders loose if project all-equity financed: • Invest 8,000 • ∆E 7,822 Loss = 178 VUB 05 Options and optimal capital structure
Milking the property • Suppose now that the shareholders decide to pay themselves a special dividend. • Example: F = 100,000, T = 5 years, r = 5%, σ = 30% V = 100,000 E = 35,958 D = 64,042 • Dividend = 10,000 ∆V = - Dividend V = 90,000 E = 28,600 D = 61,400 ∆ V = -10,000 ∆E = -7,357 ∆D =- 2,642 • Shareholders gain: • Dividend 10,000 • ∆E -7,357 VUB 05 Options and optimal capital structure
Trade-off theory Market value PV(Costs of financial distress) PV(Tax Shield) Value of all-equity firm Debt ratio VUB 05 Options and optimal capital structure
Leland 1994 • Model giving the optimal debt level when taking into account: • limited liability • interest tax shield • cost of bankruptcy • Main assumptions: • the value of the unlevered firm (VU) is known; • this value changes randomly through time according to a diffusion process with constant volatility dVU= µVU dt + VU dW; • the riskless interest rate r is constant; • bankruptcy takes place if the asset value reaches a threshold VB; • debt promises a perpetual coupon C; • if bankruptcy occurs, a fraction α of value is lost to bankruptcy costs. VUB 05 Options and optimal capital structure
VU Barrier VB Default point Time VUB 05 Options and optimal capital structure
Exogeneous level of bankruptcy • Market value of levered company V = VU + VTS(VU) - BC(VU) • VU: market value of unlevered company • VTS(VU): present value of tax benefits • BC(VU): present value of bankruptcy costs • Closed form solution: • Define pB: present value of $1 contingent on future bankruptcy VUB 05 Options and optimal capital structure
Example Value of unlevered firm VU = 100 Volatility σ = 34.64% Coupon C = 5 Tax rate TC = 40% Bankruptcy level VB = 25 Risk-free rate r = 6% Simulation: ΔVU = (.06) VUΔt + (.3464) VUΔW 1 path simulated for 100 years with Δt = 1/12 1,000 simulations Result: Probability of bankruptcy = 0.677 (within the next 100 years) Year of bankruptcy is a random variable Expected year of bankruptcy = 25.89 (see next slide) VUB 05 Options and optimal capital structure
Year of bankruptcy – Frequency distribution VUB 05 Options and optimal capital structure
Understanding pB Exact value Simulation N =number of simulations Yn = Year of bankruptcy in simulation n VUB 05 Options and optimal capital structure
Value of tax benefit Tax shield if no default PV of $1 if no default Example: VUB 05 Options and optimal capital structure
Present value of bankruptcy cost PV of $1 if default Recovery if default Example: BC(VU) = 0.50 ×25×0.25 = 3.13 VUB 05 Options and optimal capital structure
Value of debt Risk-free debt PV of $1 if default Loss given default VUB 05 Options and optimal capital structure
Endogeneous bankruptcy level • If bankrupcy takes place when market value of equity equals 0: VUB 05 Options and optimal capital structure
Notation VU value of unlevered company VBlevel of bankruptcy C perpetual coupon r riskless interest rate (const.) σ volatility (unlevered) α bankruptcy cost (fraction) TCcorporate tax rate Present value of $1 contingent on bankruptcy Value of levered company: Unlevered: VU Tax benefit: + (TCC/r)(1-pB) Bankrupcy costs: - αVB pB Value of debt Endogeneous level of bankruptcy Leland 1994 - Summary VUB 05 Options and optimal capital structure
Inside the model • Value of claim on the firm: F(VU,t) • Black-Scholes-Merton: solution of partial differential equation • When non time dependence ( ), ordinary differential equation with general solution: F = A0 + A1V + A2 V-Xwith X = 2r/σ² • Constants A0, A1and A2determined by boundary conditions: • At V = VB : D = (1 – α) VB • At V→∞ : D→ C/r VUB 05 Options and optimal capital structure
Black Scholes’ PDE and the binomial model • We have: • BS PDE : f’t + rS f’S + ½² f”SS = r f • Binomial model: p fu + (1-p) fd = ert • Use Taylor approximation: • fu = f + (u-1) Sf’S + ½ (u–1)² S² f”SS + f’tt • fd = f + (d-1) Sf’S + ½ (d–1)² S² f”SS + f’tt • u = 1 + √t + ½ ²t • d = 1 – √t + ½ ²t • ert = 1 + rt • Substituting in the binomial option pricing model leads to the differential equation derived by Black and Scholes VUB 05 Options and optimal capital structure
Unprotected and protected debt • Unprotected debt: • Constant coupon • Bankruptcy if V = VB • Endogeneous bankruptcy level: when equity falls to zero • Protected debt: • Bankruptcy if V = principal value of debt D0 • Interpretation: continuously renewed line of credit (short-term financing) VUB 05 Options and optimal capital structure
Example VUB 05 Options and optimal capital structure
References • Altman, E., Resti, A. and Sironi, A., Analyzing and Explaining Default Recovery Rates, A Report Submitted to ISDA, December 2001 • Bohn, J.R., A Survey of Contingent-Claims Approaches to Risky Debt Valuation, Journal of Risk Finance (Spring 2000) pp. 53-70 • Merton, R. On the Pricing of Corporate Debt: The Risk Structure of Interest Rates Journal of Finance, 29 (May 1974) • Merton, R. Continuous-Time Finance Basil Blackwell 1990 • Leland, H. Corporate Debt Value, Bond Covenants, and Optimal Capital Structure Journal of Finance 44, 4 (September 1994) pp. 1213- VUB 05 Options and optimal capital structure