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Annuities and No Arbitrage Pricing. Key concepts. Real investment Financial investment. Interest rate defined. Premium for current delivery. equation of the budget constraint:. Time one cash flow. = status quo. Time zero cash flow. Financing possibilities, not physical investment.
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Key concepts • Real investment • Financial investment
Interest rate defined • Premium for current delivery
equation of the budget constraint: Time one cash flow = status quo Time zero cash flow
Financing possibilities, not physical investment Time one cash flow With- drawal deposit Time zero cash flow
An investment opportunity that increases value. Time one cash flow NPV Time zero cash flow
Basic principle • Firms maximize value • Owners maximize utility • Separately
Justification • Real investment with positive NPV shifts consumption opportunities outward. • Financial investment satisfies the owner’s time preferences.
Why use interest rates • Instead of just prices • Coherence
Example: pure discount bond • Definition: A pure discount bond pays 1000 at maturity and has no interest payments before then. • Price is the PV of that 1000 cash flow, using the market rate specific to the asset.
Example continued • Ten-year discount bond: price is 426.30576 • Five-year discount bond: price is 652.92095 • Are they similar or different? • Similar because they have the SAME interest rate r = .089 (i.e. 8.9%)
Calculations • 652.92095 = 1000 / (1+.089)^5 • Note: ^ is spreadsheet notation for raising to a power • 426.30576 = 1000 / (1+.089)^10
More realistically • For the ten-year discount bond, the price is 422.41081 (not 426.30576). • The ten-year rate is (1000/422.41081)^.1 - 1 = .09The .1 power is the tenth root. • The longer bond has a higher interest rate. Why? • Because more time means more risk.
Definitions • Coupon -- the amount paid periodically • Coupon rate -- the coupon times annual payments divided by 1000 • Same as for mortgage payments
No arbitrage principle • Market prices must admit no profitable, risk-free arbitrage. • No money pumps. • Otherwise, acquisitive investors would exploit the arbitrage indefinitely.
Example • Coupons sell for 450 • Principal sells for 500 • The bond MUST sell for 950. • Otherwise, an arbitrage opportunity exists. • For instance, if the bond sells for 920… • Buy the bond, sell the stripped components. Profit 30 per bond, indefinitely. • Similarly, if the bond sells for 980 …
Two parts of a bond • Pure discount bond • A repeated constant flow -- an annuity
Stripped coupons and principal • Treasury notes (and some agency bonds) • Coupons (assembled) sold separately, an annuity. • Stripped principal is a pure discount bond.
Annuity • Interest rate per period, r. • Size of cash flows, C. • Maturity T. • If T=infinity, it’s called a perpetuity.
Market value of a perpetuity • Start with a perpetuity.
Value of a perpetuity is C*(1/r) • In spreadsheet notation, * is the sign for multiplication. • Present Value of Perpetuity Factor, PVPF(r) = 1/r • It assumes that C = 1. • For any other C, multiply PVPF(r) by C.
Value of an annuity • C*(1/r)[1-1/(1+r)^T] • Present value of annuity factor • PVAF(r,T) = (1/r)[1-1/(1+r)^T] • or ArT
Explanation • Value of annuity = • difference in values of perpetuities. • One starts at time 1, • the other starts at time T + 1.
Values • P.V. of Perp at 0 = 1/r • P.V. of Perp at T = (1/r) 1/(1+r)^T • Value of annuity = difference = (1/r)[1-1/(1+r)^T ]
Compounding • 12% is not 12% … ? • … when it is compounded.
Example: which is better? • Wells Fargo: 8.3% compounded daily • World Savings: 8.65% uncompounded
Solution • Compare the equivalent annual rates • World Savings: EAR = .0865 • Wells Fargo: (1+.083/365)365 -1 = .0865314
When to cut a tree • Application of continuous compounding • A tree growing in value. • The land cannot be reused. • Discounting continuously. • What is the optimum time to cut the tree? • The time that maximizes NPV.
Numerical example • Cost of planting = 100 • Value of tree -100+25t • Interest rate .05 • Maximize (-100+25t)exp(-.05t) • Check second order conditions • First order condition .05 = 25/(-100+25t) • t = 24 value = 500
Example continued • Present value of the tree =500*exp(-.05*24) = 150.5971. • Greater than cost of 100. • NPV = 50.5971 • Market value of a partly grown tree at time t < 24 is 150.5971*exp(.05*t) • For t > 24 it is -100+25*t
Example: Cost of College • Annual cost = 25000 • Paid when? • Make a table of cash flows
Timing • Obviously simplified
Present value at time zero • 25+25*PVAF(.06,3) • =91.825298
Saving for college • Start saving 16 years before matriculation. • How much each year? • Make a table.
Solution outlined • Find PV of target sum, that is, take 91.825 and discount back to time 0. • Divide by (1.06)^16 • PV of savings =C+C*PVAF(.06,16) • Equate and solve for C.
Numerical Solution • PV of target sum = 36.146687 • PV of savings = C+C*10.105895 • C = 3.2547298
Alternative solution outlined • Need 91.825 at time 16. • FV of savings =(1.06)^16 *(C+C*PVAF(.06,16)) • Equate and solve for C.
Numerical Solution • Future target sum = 91.825 • FV of savings = (1.06)^16*(C+C*10.105895) • 91.825 = C*((1.06)^16)*(1+10.105895) • C = 3.2547298
Review question • The interest rate is 6%, compounded monthly. • You set aside $100 at the end of each month for 10 years. • How much money do you have at the end?
Answer in two steps • Step 1. Find PDV of the annuity. • .005 per month • 120 months • PVAF = 90.073451 • PVAF*100 = 9007.3451 • Step 2. Translate to money of time 120. • [(1.005)^120]*9007.3451 = 16387.934