1. Chapter 12 Bond Prices and the Importance of Duration

2. Outline Introduction Review of bond principles
Bond pricing and returns
Bond risk
The meaning of bond diversification
Choosing bonds
Example: monthly retirement income

3. Introduction
The investment characteristics of bonds range completely across the risk/return spectrum
As part of a portfolio, bonds provide both stability and income
Capital appreciation is not usually a motive for acquiring bonds

4. Review of Bond Principles
Identification of bonds
Classification of bonds
Terms of repayment
Bond cash flows
Convertible bonds
Registration

5. Identification of Bonds
A bond is identified by:
The issuer
The coupon
The maturity
For example, five IBM “eights of 10” means $5,000 par IBM bonds with an 8% coupon rate and maturing in 2010

6. Classification of Bonds
Introduction
Issuer
Security
Term

7. Introduction The bond indenture describes the details of a bond issue:
Description of the loan
Terms of repayment
Collateral
Protective covenants
Default provisions

8. Issuer
Bonds can be classified by the nature of the organizations initially selling them:
Corporation
Federal, state, and local governments
Government agencies
Foreign corporations or governments

9. Definition
The security of a bond refers to what backs the bond (what collateral reduces the risk of the loan)

10. Unsecured Debt Governments:
Full faith and credit issues (general obligation issues) is government debt without specific assets pledged against it
E.g., U.S. Treasury bills, notes, and bonds

11. Unsecured Debt (cont’d)
Corporations:
Debentures are signature loans backed by the good name of the company
Subordinated debentures are paid off after original debentures

12. Secured Debt Municipalities issue: Revenue bonds Assessment bonds
Interest and principal are repaid from revenue generated by the project financed by the bond
Assessment bonds
Benefit a specific group of people, who pay an assessment to help pay principal and interest

13. Secured Debt (cont’d) Corporations issue: Mortgages
Well-known securities that use land and buildings as collateral
Collateral trust bonds
Backed by other securities
Equipment trust certificates
Backed by physical assets

14. Term The term is the original life of the debt security
Short-term securities have a term of one year or less
Intermediate-term securities have terms ranging from one year to ten years
Long-term securities have terms longer than ten years

15. Terms of Repayment
Interest only
Sinking fund
Balloon
Income bonds

16. Interest Only Periodic payments are entirely interest
The principal amount of the loan is repaid at maturity

17. Sinking Fund
A sinking fund requires the establishment of a cash reserve for the ultimate repayment of the bond principal
The borrower can:
Set aside a potion of the principal amount of the debt each year
Call a certain number of bonds each year

18. Balloon
Balloon loans partially amortize the debt with each payment but repay the bulk of the principal at the end of the life of the debt
Most balloon loans are not marketable

19. Income Bonds Income bonds pay interest only if the firm earns it
For example, an income bond may be issued to finance an income-producing project

20. Bond Cash Flows Annuities Zero coupon bonds Variable rate bonds
Consols

21. Annuities
An annuity promises a fixed amount on a regular periodic schedule for a finite length of time
Most bonds are annuities plus an ultimate repayment of principal

22. Zero Coupon Bonds
A zero coupon bond has a specific maturity date when it returns the bond principal
A zero coupon bond pays no periodic income
The only cash inflow is the par value at maturity

23. Variable Rate Bonds
Variable rate bonds allow the rate to fluctuate in accordance with a market index
For example, U.S. Series EE savings bonds

24. Consols Consols pay a level rate of interest perpetually:
The bond never matures
The income stream lasts forever
Consols are not very prevalent in the U.S.

25. Definition
A convertible bond gives the bondholder the right to exchange them for another security or for some physical asset
Once conversion occurs, the holder cannot elect to reconvert and regain the original debt security

26. Security-Backed Bonds
Security-backed convertible bonds are convertible into other securities
Typically common stock of the company that issued the bonds
Occasionally preferred stock of the issuing firm, common stock of another firm, or shares in a subsidiary company

27. Commodity-Backed Bonds
Commodity-backed bonds are convertible into a tangible asset
For example, silver or gold

28. Bearer Bonds Bearer bonds:
Do not have the name of the bondholder printed on them
Belong to whoever legally holds them
Are also called coupon bonds
The bond contains coupons that must be clipped
Are no longer issued in the U.S.

29. Registered Bonds Registered bonds show the bondholder’s name
Registered bondholders receive interest checks in the mail from the issuer

30. Book Entry Bonds
The U.S. Treasury and some corporation issue bonds in book entry form only
Holders do not take actual delivery of the bond
Potential holders can:
Open an account through the Treasury Direct System at a Federal Reserve Bank
Purchase a bond through a broker

31. Bond Pricing and Returns
Introduction
Valuation equations
Yield to maturity
Realized compound yield
Current yield
Term structure of interest rates
Spot rates

32. Bond Pricing and Returns (cont’d)
The conversion feature
The matter of accrued interest

33. Introduction
The current price of a bond is the market’s estimation of what the expected cash flows are worth in today’s dollars
There is a relationship between:
The current bond price
The bond’s promised future cash flows
The riskiness of the cash flows

34. Valuation equations Annuities Zero coupon bonds Variable rate bonds
Consols

35. Annuities
For a semiannual bond:

36. Annuities (cont’d)
Separating interest and principal components:

37. Annuities (cont’d) Example
A bond currently sells for $870, pays $70 per year (Paid semiannually), and has a par value of $1,000. The bond has a term to maturity of ten years.
What is the yield to maturity?

38. Annuities (cont’d) Example (cont’d)
Solution: Using a financial calculator and the following input provides the solution:
N = 20
PV = $870
PMT = $35
FV = $1,000
CPT I = 4.50
This bond’s yield to maturity is 4.50% x 2 = 9.00%.

39. Zero Coupon Bonds
For a zero-coupon bond (annual and semiannual compounding):

40. Zero Coupon Bonds (cont’d)
Example
A zero coupon bond has a par value of $1,000 and currently sells for $400. The term to maturity is twenty years.
What is the yield to maturity (assume semiannual compounding)?

41. Zero Coupon Bonds (cont’d)
Example (cont’d)
Solution:

43. Variable Rate Bonds
The valuation equation must allow for variable cash flows
You cannot determine the precise present value of the cash flows because they are unknown:

44. Consols
Consols are perpetuities:

45. Consols (cont’d) Example
A consol is selling for $900 and pays $60 annually in perpetuity.
What is this consol’s rate of return?

46. Consols (cont’d)
Example (cont’d)
Solution:

47. Yield to Maturity
Yield to maturity captures the total return from an investment
Includes income
Includes capital gains/losses
The yield to maturity is equivalent to the internal rate of return in corporate finance

50. Realized Compound Yield
The effective annual yield is useful to compare bonds to investments generating income on a different time schedule

51. Realized Compound Yield (cont’d)
Example
A bond has a yield to maturity of 9.00% and pays interest semiannually.
What is this bond’s effective annual rate?

52. Realized Compound Yield (cont’d)
Example (cont’d)
Solution:

53. Current Yield The current yield:
Measures only the return associated with the interest payments
Does not include the anticipated capital gain or loss resulting from the difference between par value and the purchase price

54. Current Yield (cont’d)
For a discount bond, the yield to maturity is greater than the current yield
For a premium bond, the yield to maturity is less than the current yield

55. Current Yield (cont’d)
Example
A bond pays annual interest of $70 and has a current price of $870.
What is this bond’s current yield?

56. Current Yield (cont’d)
Example (cont’d)
Solution:
Current yield = $70/$870 = 8.17%

57. Yield Curve The yield curve:
Is a graphical representation of the term structure of interest rates
Relates years until maturity to the yield to maturity
Is typically upward sloping and gets flatter for longer terms to maturity

58. Information Used to Build A Yield Curve

59. Theories of Interest Rate Structure
Expectations theory
Liquidity preference theory
Inflation premium theory

60. Expectations Theory
According to the expectations theory of interest rates, investment opportunities with different time horizons should yield the same return:

61. Expectations Theory (cont’d)
Example
An investor can purchase a two-year CD at a rate of 5 percent. Alternatively, the investor can purchase two consecutive one-year CDs. The current rate on a one-year CD is 4.75 percent.
According to the expectations theory, what is the expected one-year CD rate one year from now?

62. Expectations Theory (cont’d)
Example (cont’d)
Solution:

63. Liquidity Preference Theory
Proponents of the liquidity preference theory believe that, in general:
Investors prefer to invest short term rather than long term
Borrowers must entice lenders to lengthen their investment horizon by paying a premium for long-term money (the liquidity premium)
Under this theory, forward rates are higher than the expected interest rate in a year

64. Inflation Premium Theory
The inflation premium theory states that risk comes from the uncertainty associated with future inflation rates
Investors who commit funds for long periods are bearing more purchasing power risk than short-term investors
More inflation risk means longer-term investment will carry a higher yield

65. Spot Rates
Spot rates:
Are the yields to maturity of a zero coupon security
Are used by the market to value bonds
The yield to maturity is calculated only after learning the bond price
The yield to maturity is an average of the various spot rates over a security’s life

66. Spot Rates (cont’d) Spot Rate Curve Yield to Maturity Interest Rate
Time Until the Cash Flow

67. Spot Rates (cont’d) Example
A six-month T-bill currently has a yield of 3.00%. A one-year T-note with a 4.20% coupon sells for 102.
Use bootstrapping to find the spot rate six months from now.

68. Spot Rates (cont’d) Example (cont’d)
Solution: Use the T-bill rate as the spot rate for the first six months in the valuation equation for the T-note:

69. The Conversion Feature
Convertible bonds give their owners the right to exchange the bonds for a pre-specified amount or shares of stock
The conversion ratio measures the number of shares the bondholder receives when the bond is converted
The par value divided by the conversion ratio is the conversion price
The current stock price multiplied by the conversion ratio is the conversion value

70. The Conversion Feature (cont’d)
The market price of a bond can never be less than its conversion value
The difference between the bond price and the conversion value is the premium over conversion value
Reflects the potential for future increases in the common stock price
Mandatory convertibles convert automatically into common stock after three or four years

71. The Matter of Accrued Interest
Bondholders earn interest each calendar day they hold a bond
Firms mail interest payment checks only twice a year
Accrued interest refers to interest that has accumulated since the last interest payment date but which has not yet been paid

72. The Matter of Accrued Interest (cont’d)
At the end of a payment period, the issuer sends one check for the entire interest to the current bondholder
The bond buyer pays the accrued interest to the seller
The bond sells receives accrued interest from the bond buyer

73. The Matter of Accrued Interest (cont’d)
Example
A bond with an 8% coupon rate pays interest on June 1 and December 1. The bond currently sells for $920.
What is the total purchase price, including accrued interest, that the buyer of the bond must pay if he purchases the bond on August 10?

74. The Matter of Accrued Interest (cont’d)
Example (cont’d)
Solution: The accrued interest for 71 days is:
$80/365 x 71 = $15.56
Therefore, the total purchase price is:
$920 + $15.56 = $935.56

76. Bond Risk Price risks Convenience risks
Malkiel’s interest rate theories
Duration as a measure of interest rate risk

77. Price Risks
Interest rate risk
Default risk

78. Interest Rate Risk
Interest rate risk is the chance of loss because of changing interest rates
The relationship between bond prices and interest rates is inverse
If market interest rates rise, the market price of bonds will fall

79. Default Risk
Default risk measures the likelihood that a firm will be unable to pay the principal and interest on a bond
Standard & Poor’s Corporation and Moody’s Investor Service are two leading advisory services monitoring default risk

80. Default Risk (cont’d)
Investment grade bonds are bonds rated BBB or above
Junk bonds are rated below BBB
The lower the grade of a bond, the higher its yield to maturity

81. Convenience Risks Definition Call risk Reinvestment rate risk
Marketability risk

82. Definition
Convenience risk refers to added demands on management time because of:
Bond calls
The need to reinvest coupon payments
The difficulty in trading a bond at a reasonable price because of low marketability

83. Call Risk If a company calls its bonds, it retires its debt early
Call risk refers to the inconvenience of bondholders associated with a company retiring a bond early
Bonds are usually called when interest rates are low

84. Call Risk (cont’d) Many bond issues have: Call protection
A period of time after the issuance of a bond when the issuer cannot call it
A call premium if the issuer calls the bond
Typically begins with an amount equal to one year’s interest and then gradually declining to zero as the bond approaches maturity

85. Reinvestment Rate Risk
Reinvestment rate risk refers to the uncertainty surrounding the rate at which coupon proceeds can be invested
The higher the coupon rate on a bond, the higher its reinvestment rate risk

86. Marketability Risk
Marketability risk refers to the difficulty of trading a bond:
Most bonds do not trade in an active secondary market
The majority of bond buyers hold bonds until maturity
Low marketability bonds usually carry a wider bid-ask spread

87. Malkiel’s Interest Rate Theorems
Definition
Theorem 1
Theorem 2
Theorem 3
Theorem 4
Theorem 5

88. Definition
Malkiel’s interest rate theorems provide information about how bond prices change as interest rates change
Any good portfolio manager knows Malkiel’s theorems

89. Theorem 1 Bond prices move inversely with yields:
If interest rates rise, the price of an existing bond declines
If interest rates decline, the price of an existing bond increases

90. Theorem 2
Bonds with longer maturities will fluctuate more if interest rates change
Long-term bonds have more interest rate risk

92. Theorem 3 Higher coupon bonds have less interest rate risk
Money in hand is a sure thing while the present value of an anticipated future receipt is risky

93. Theorem 4
When comparing two bonds, the relative importance of Theorem 2 diminishes as the maturities of the two bonds increase
A given time difference in maturities is more important with shorter-term bonds

94. Theorem 5
Capital gains from an interest rate decline exceed the capital loss from an equivalent interest rate increase

95. Duration as A Measure of Interest Rate Risk
The concept of duration
Calculating duration

96. The Concept of Duration
For a noncallable security:
Duration is the weighted average number of years necessary to recover the initial cost of the bond
Where the weights reflect the time value of money

97. The Concept of Duration (cont’d)
Duration is a direct measure of interest rate risk:
The higher the duration, the higher the interest rate risk

98. Calculating Duration
The traditional duration calculation:

100. Calculating Duration (cont’d)
The closed-end formula for duration:

101. Calculating Duration (cont’d)
Example
Consider a bond that pays $100 annual interest and has a remaining life of 15 years. The bond currently sells for $985 and has a yield to maturity of 10.20%.
What is this bond’s duration?

102. Calculating Duration (cont’d)
Example (cont’d)
Solution: Using the closed-form formula for duration:

105. Bond Selection - Introduction
In most respects selecting the fixed-income components of a portfolio is easier than selecting equity securities
There are ways to make mistakes with bond selection

106. The Meaning of Bond Diversification
Introduction
Default risk
Dealing with the yield curve
Bond betas

107. Introduction It is important to diversify a bond portfolio
Diversification of a bond portfolio is different from diversification of an equity portfolio
Two types of risk are important:
Default risk
Interest rate risk

108. Default Risk
Default risk refers to the likelihood that a firm will be unable to repay the principal and interest of a loan as agreed in the bond indenture
Equivalent to credit risk for consumers
Rating agencies such as S&P and Moody’s function as credit bureaus for credit issuers

109. Default Risk (cont’d) To diversify default risk:
Purchase bonds from a number of different issuers
Do not purchase various bond issues from a single issuer
E.g., Enron had 20 bond issues when it went bankrupt

110. Dealing With the Yield Curve
The yield curve is typically upward sloping
The longer a fixed-income security has until maturity, the higher the return it will have to compensate investors
The longer the average duration of a fund, the higher its expected return and the higher its interest rate risk

111. Dealing With the Yield Curve (cont’d)
The client and portfolio manager need to determine the appropriate level of interest rate risk of a portfolio

112. Bond Betas The concept of bond betas:
States that the market prices a bond according to its level of risk relative to the market average
Has never become fully accepted
Measures systematic risk, while default risk and interest rate risk are more important

113. Choosing Bonds Client psychology and bonds selling at a premium
Call risk
Constraints

114. Client Psychology and Bonds Selling at A Premium
Premium bonds held to maturity are expected to pay higher coupon rates than the market rate of interest
Premium bond held to maturity will decline in value toward par value as the bond moves towards its maturity date

115. Client Psychology & Bonds Selling at A Premium (cont’d)
Clients may not want to buy something they know will decline in value
There is nothing wrong with buying bonds selling at a premium

116. Call Risk If a bond is called:
The funds must be reinvested
The fund manager runs the risk of having to make adjustments to many portfolios all at one time
There is no reason to exclude callable bonds categorically from a portfolio
Avoid making extensive use of a single callable bond issue

117. Constraints Specifying return Specifying grade
Specifying average maturity
Periodic income
Maturity timing
Socially responsible investing

118. Specifying Return To increase the expected return on a bond portfolio:
Choose bonds with lower ratings
Choose bonds with longer maturities
Or both

119. Specifying Grade
A legal list specifies securities that are eligible investments
E.g., investment grade only
Portfolio managers take the added risk of noninvestment grade bonds only if the yield pickup is substantial

120. Specifying Grade (cont’d)
Conservative organizations will accept only U.S. government or AAA-rated corporate bonds
A fund may be limited to no more than a certain percentage of non-AAA bonds

121. Specifying Average Maturity
Average maturity is a common bond portfolio constraint
The motivation is concern about rising interest rates
Specifying average duration would be an alternative approach

122. Periodic Income
Some funds have periodic income needs that allow little or not flexibility
Clients will want to receive interest checks frequently
The portfolio manager should carefully select the bonds in the portfolio

123. Maturity Timing Maturity timing generates income as needed
Sometimes a manager needs to construct a bond portfolio that matches a particular investment horizon
E.g., assemble securities to fund a specific set of payment obligations over the next ten years
Assemble a portfolio that generates income and principal repayments to satisfy the income needs

124. Socially Responsible Investing
Some clients will ask that certain types of companies not be included in the portfolio
Examples are nuclear power, military hardware, “vice” products

125. Example: Monthly Retirement Income
The problem
Unspecified constraints
Using S&P’s Bond Guide
Solving the problem

126. The Problem A client has: Primary objective: growth of income
Secondary objective: income
$1,100,000 to invest
Inviolable income needs of $4,000 per month

127. The Problem (cont’d) You decide:
To invest the funds between common stocks and debt securities
To invest in ten common stock in the equity portion (see next slide)
You incur $1,500 in brokerage commissions

128. The Problem (cont’d) Stock Value Qrtl Div. Payment Month 3,000 AAC
$51,000
$380
Jan./April/July/Oct.
1,000 BBL
50,000
370
2,000 XXQ
49,000
400
Feb./May/Aug./Nov.
5,000 XZ
52,000
270
March/June/Sept./Dec.
7,000 MCDL
53,000 --
1,000 ME
2,000 LN
51,000
500
4,000 STU
47,000
260
3,000 LLZ
290
6,000 MZN
43,000
170
Total
$494,000
$3,010

129. The Problem (cont’d) Characteristics of the fund:
Quarterly dividends total $3,001 ($12,004 annually)
The dividend yield on the equity portfolio is 2.44%
Total annual income required is $48,000 or 4.36% of fund
Bonds need to have a current yield of at least 6.28%

130. Unspecified Constraints
The task is meeting the minimum required expected return with the least possible risk
You don’t want to choose CC-rated bonds
You don’t want the longest maturity bonds you can find

131. Using S&P’s Bond Guide Figure 11-4 is an excerpt from the Bond Guide:
Indicates interest payment dates, coupon rates, and issuer
Provides S&P ratings
Provides current price, current yield

132. Using S&P’s Bond Guide (cont’d)

133. Solving the Problem Setup
Dealing with accrued interest and commissions
Choosing the bonds
Overspending
What about convertible bonds?

134. Setup You have two constraints:
Include only bonds rated BBB or higher
Keep the average maturities below fifteen years
Set up a worksheet that enables you to pick bonds to generate exactly $4,000 per month (see next slide)

135. Setup (cont’d) Security Price Jan. Feb. March April May June 3,000 AAC
$51,000
$380
1,000 BBL
50,000
370
2,000 XXQ
49,000
$400
5,000 XZ
52,000
$270
7,000 MCDL
53,000
1,000 ME
2,000 LN
51,000
500
4,000 STU
47,000
260
3,000 LLZ
290
6,000 MZN
43,000
170
Equities
$494,000
$1,420
$1,060
$530

136. Dealing With Accrued Interest and Commissions
Bond prices are typically quoted on a net basis (already include commissions)
Calculate accrued interest using the mid-term heuristic
Assume every bond’s accrued interest is half of one interest check

137. Choosing the Bonds The following slide shows one possible solution:
Stock cost: $494,000
Bond cost: $557,130
Accrued interest: $9,350
Stock commissions: $1,500
Do you think this solution could be improved?

138. Bonds Security Price Jan. Feb. March April May June
$80,000 Empire 71/2s02
$86,400
$3,000
$80,000 Energen 8s07
82,900
$3,200
$100,000 Enhance 61/4s03
105,500
$3,370
$80,000 Enron 65/8s03
84,500
$2,650
$90,000 Enron 6.7s06
97,200
$3,010
$100,000 Englehard 6.95s28
100,630
$3,470
Bonds subtotal
$557,130
Total income
$4,420
$4,260
$3,900
$4,070
$4,000

139. Overspending
The total of all costs associated with the portfolio should not exceed the amount given to you by the client to invest
The money the client gives you establishes another constraint

140. What About Convertible Bonds?
Convertible bonds can be included in a portfolio
Useful for a growth of income objective
People buy convertible bonds in hopes of price appreciation
Useful if you otherwise meet your income constraints

141. Immunization Strategies
A portfolio of bonds is said to be immunized (from interest rate risk) if its payoff at some future date is independent of the future levels of interest rates.
Immunization is closely related to the concept of duration.

142. Immunization consists of matching the duration of the portfolio’s assets and liabilities (obligations).
Suppose a firm has a future obligation Q. The prevailing interest rate is r, and the liability is N periods away.
The present value of this liability is denoted by V0=Q/(1+r)N.

143. Now suppose that the firm is currently hedging this liability with a bond whose value VB = V0 and whose coupon payments are denoted by P1,…,PM.
We thus have:

144. Suppose now that interest rates change from r to r+Dr
Suppose now that interest rates change from r to r+Dr. The new values of the future obligation and of the bond are:

145. Rearranging terms and recalling that V0=VB yields the following expression:
The left-hand side represents the duration of the bond, while the right-hand side represents the duration of the obligation (Since the obligation consisted of only one payment, the duration is its maturity).

146. In conclusion, in order for a portfolio to be immunized, you need to have:
DURATIONASSETS = DURATIONLIABILITIES
Caveat: this works only if the interest rates of various maturities all change in the same manner, i.e. if the yield curve shifts upward or downward in a parallel shift.

147. Immunization Example
You need to immunize an obligation whose present value V0 is $1,000. The payment is to be made 10 years from now, and the current interest rate is 6%. The payment is thus the future value of 1,000 at 6%, therefore it is:
1,000(1.06)10 = $1,790.85
The Excel spreadsheet on the next slide shows three bonds that you have at your disposition to immunize the liability.

150. Values 10 years later, assuming interest rates do not change
(The goal of getting $1, is still met)

151. Values 10 years later, assuming interest rates change to 5% right after we buy the bonds
(The goal of getting $1, is not met by Bond 1 anymore)

152. Observations
If interest rates go down to 5%, Bond 1 does not meet the requirement anymore.
Bond 3, on the other hand, exceeds the payment that must be made in year 10.
The ability of Bond 2 to meet the obligation is barely affected. Why? Because its duration is 10 years, exactly matching the duration of the liability. Pick Bond 2.

153. We can compute and plot the bonds’ terminal values in year 10