Chapter 5
Interest Rates
Chapter Outline
Interest Rate Quotes and Adjustments
Application: Discount Rates and Loans
The Determinants of Interest Rates
Risk and Taxes
The Opportunity Cost of Capital
Learning Objectives
Define effective annual rate and annual percentage rate.
Given an effective annual rate, compute the n-period effective annual rate.
Convert an annual percentage rate into an effective annual rate, given the number of compounding periods.
Describe the relation between nominal and real rates of interest.
Given two of the following, compute the third: nominal rate, real rate, and inflation rate.
Learning Objectives (cont'd)
Describe the effect of higher interest rates on net present values in the economy.
Explain how to choose the appropriate discount rate for a given stream of cash flows, according to the investment horizon.
Discuss the determinants of the shape of the yield curve.
Explain why Treasury securities are considered risk free, and describe the impact of default risk on interest rates.
Given the other two, compute the third: after-tax interest rate, tax rate, and before-tax interest rate.
Interest Rate Quotes and Adjustments
The Effective Annual Rate
Indicates the total amount of interest that will be earned at the end of one year
Considers the effect of compounding
Also referred to as the effective annual yield (EAY) or annual percentage yield (APY)
Interest Rate Quotes
and Adjustments (cont'd)
Adjusting the Discount Rate to Different Time Periods
Earning a 5% return annually is not the same as earning % every six months.
General Equation for Discount Rate Period Conversion
() – 1= – 1 = .0247 = %
Note: n = since we are solving for the six month (or 1/2 year) rate
Textbook Example
Textbook Example (cont'd)
Alternative Example
Problem
Suppose an investment pays interest quarterly with the interest rate quoted as an effective annual rate (EAR) of 9%.
What amount of interest will you earn each quarter?
If you have no money in the bank today, how much will you need to save at the end of each quarter to accumulate $25,000 in 5 years?
Alternative Example
Solution
From Equation , a 9% EAR is approximately equivalent to earning ()1/4 – 1 = % per quarter.
To determine the amount to save each quarter to reach the goal of $25,000 in five years, we must determine the quarterly payment, C:
Annual Percentage Rates
The annual percentage rate (APR), indicates the amount of simple interest earned in one year.
Simple interest is the amount of interest earned without the effect of compounding.
The APR is typically less than the effective annual rate (EAR).
Annual Percentage Rates (cont'd)
The APR itself cannot be used as a discount rate.
The APR with k compounding periods is a way of quoting the actual interest earned each compounding period:
Annual Percentage Rates (cont'd)
Converting an APR to an EAR
The EAR increases with the frequency of compounding.
Continuous compounding is compounding every instant.
Annual Percentage Rates (cont'd)
A 6% APR with continuous compounding results in an EAR of approximately %.
Table Effective Annual Rates for a 6% APR with Different Compounding Periods
Textbook Example
Textbook Example (cont'd)
Alternative Example
Problem
A firm is considering purchasing or leasing a luxury automobile for the CEO. The vehicle is expected to last 3 years. You can buy the car for $65,000 up front , or you can lease it for $1,800 per month for 36 months. The firm can borrow at an interest rate of 8% APR with quarterly compounding. Should you purchase the system outright or pay $1,800 per month?
Alternative Example (cont’d)
Solution
The first step is to compute the discount rate that corresponds to monthly compounding. To convert an 8% rate compounded quarterly to a monthly discount rate, compound the quarterly rate using Equations and :
Alternative Example (cont’d)
Solution
Given a monthly discount rate of %, the present value of the 36 monthly payments can be computed:
Paying $1,800 per month for 36 months is equivalent to paying $57,486 today. This is $65,000 - $57,486 = $7,514 lower than the cost of purchasing the system, so it is better to lease the vehicle rather than buy it.
Application: Discount Rates and Loans
Computing Loan Payments
Payments are made at a set interval, typically monthly.
Each payment made includes the interest on the loan plus some part of the loan balance.
All payments are equal and the loan is fully repaid with the final payment.
Application: Discount Rates
and Loans (cont'd)
Computing Loan Payments
Consider a $30,000 car loan with 60 equal monthly payments, computed using a % APR with monthly compounding.
% APR with monthly compounding corresponds to a one-month discount rate of % / 12 = %.
Application: Discount Rates
and Loans (cont'd)
Computing Loan Payments
Financial Calculator Solution
Application: Discount Rates
and Loans (cont'd)
Computing the Outstanding Loan Balance
One can compute the outstanding loan balance by calculating the present value of the remaining loan payments.
Textbook Example
Textbook Example (cont'd)
The Determinants of Interest Rates
Inflation and Real Versus Nominal Rates
Nominal Interest Rate: The rates quoted by financial institutions and used for discounting or compounding cash flows
Real Interest Rate: The rate of growth of your purchasing power, after adjusting for inflation
The Determinants
of Interest Rates (cont'd)
The Real Interest Rate
Textbook Example
Textbook Example (cont'd)
Alternative Example
Problem
In the year 2008, the average 1-year Treasury Constant Maturity rate was about % and the rate of inflation was about %.
What was the real interest rate in 2008?
Alternative Example
Solution
Using Equation , the real interest rate in 2008 was:
(% − %) ÷ () = %
Which is (approximately) equal to the difference between the nominal rate and inflation: % – % = %
Figure . Interest Rates
and Inflation Rates,1960–2009
Investment and Interest Rate Policy
An increase in interest rates will typically reduce the NPV of an investment.
Consider an investment that requires an initial investment of $10 million and generates a cash flow of $3 million per year for four years. If the interest rate is 5%, the investment has an NPV of:
Investment and Interest Rate
Policy (cont'd)
If the interest rate rises to 9%, the NPV becomes negative and the investment is no longer profitable:
Monetary Policy, Deflation, and the 2008 Financial Crisis
When the 2008 financial crisis struck, the Federal Reserve responded by cutting its short-term interest rate target to 0%.
While this use of monetary policy is generally quite effective, because consumer prices were falling in late 2008, the inflation rate was negative, and so even with a 0% nominal interest rate the real interest rate remained positive.
The Yield Curve and Discount Rates
Term Structure: The relationship between the investment term and the interest rate
Yield Curve: A graph of the term structure
Figure Term Structure of Risk-Free . Interest Rates, November 2006, 2007, and 2008
The Yield Curve
and Discount Rates (cont'd)
The term structure can be used to compute the present and future values of a risk-free cash flow over different investment horizons.
Present Value of a Cash Flow Stream Using a Term Structure of Discount Rates
Textbook Example
Textbook Example (cont'd)
Alternative Example
Problem
Compute the present value of a risk-free three-year annuity of $500 per year, given the following yield curve:
Alternative Example
Solution
Each cash flow must be discounted by the corresponding interest rate:
The Yield Curve and the Economy
Interest Determination
The Federal Reserve determines very short-term interest rates through its influence on the federal funds rate, which is the rate at which banks can borrow cash reserves on an overnight basis.
All other interest rates on the yield curve are set in the market and are adjusted until the supply of lending matches the demand for borrowing at each loan term.
The Yield Curve and the Economy
Interest Rate Expectations
The shape of the yield curve is influenced by interest rate expectations.
An inverted yield curve indicates that interest rates are expected to decline in the future.
Because interest rates tend to fall in response to an economic slowdown, an inverted yield curve is often interpreted as a negative forecast for economic growth.
Each of the last six recessions in the United States was preceded by a period in which the yield curve was inverted.
The yield curve tends to be sharply increasing as the economy comes out of a recession and interest rates are expected to rise.
Figure Short-Term Versus Long-Term . Interest Rates and Recessions
Textbook Example
Textbook Example (cont'd)
Risk and Taxes
Risk and Interest Rates
. Treasury securities are considered “risk-free.” All other borrowers have some risk of default, so investors require a higher rate of return.
Figure Interest Rates on Five-
Year Loans for Various Borrowers, March 2009
Textbook Example
Textbook Example (cont'd)
After-Tax Interest Rates
Taxes reduce the amount of interest an investor can keep, and we refer to this reduced amount as the after-tax interest rate.
Textbook Example
Textbook Example (cont'd)
The Opportunity Cost of Capital
Opportunity Cost of Capital: The best available expected return offered in the market on an investment of comparable risk and term to the cash flow being discounted
Also referred to as Cost of Capital
Chapter Quiz
What is the difference between and EAR and an APR quote?
Why can’t the APR itself be used as a discount rate?
What is an amortizing loan?
What is the difference between a nominal and real interest rate?
Why do corporations pay higher interest rates on their loans then the . government?
Chapter Quiz (cont’d)
How do taxes affect the interest earned on an investment? What about the interest paid on a loan?
What is the opportunity cost of capital?
Chapter 5
Appendix
Continuous Rates and Cash Flows
Discount Rate of a Continuously Compounded APR
Some investments compound more frequently than daily.
As we move from daily to hourly to compounding every second, we approach the limit of continuous compounding, in which we compound every instant.
The EAR for a Continuously Compounded APR
Continuous Rates and Cash Flows (cont’d)
Discount Rate of a Continuously Compounded APR
Alternatively, if we know the EAR and want to find the corresponding continuously compounded APR, the formula is:
The Continuously Compounded APR for an EAR
Continuously compounded rates are not often used in practice.
Continuous Rates and Cash Flows (cont’d)
Continuously Arriving Cash Flows
Consider the cash flows of an online book retailer. Suppose the firm forecasts cash flows of $10 million per year. The $10 million will be received throughout each year, not at year-end, that is, the $10 million is paid continuously throughout the year.
We can compute the present value of cash flows that arrive continuously using a version of the growing perpetuity formula.
Continuous Rates and Cash Flows (cont’d)
Continuously Arriving Cash Flows
If cash flows arrive, starting immediately, at an initial rate of $C per year, and if the cash flows grow at rate g per year, then given a discount rate of r per year, the present value of the cash flows is:
Present Value of a Continuously Growing Perpetuity
where rcc=ln(1+r) and gcc = ln(1+g) are the discount and growth rates expressed as continuously APRs, respectively.
Continuous Rates and Cash Flows (cont’d)
Continuously Arriving Cash Flows
The present value of a continuously growing perpetuity can be approximated by:
where is the total cash received during the first year.
Textbook Example
Textbook Example
Chapter Appendix Quiz
What is a continuously compounded EAR? How does this differ from a continuously compounded APR?
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