bonds - finance departmentfinance.wharton.upenn.edu/~mrrobert/resources/teaching/corpfinu… · baa...

11

1Copyright © Michael R. Roberts

Bonds

Finance 100

Prof. Michael R. Roberts


Topic Overview

Introduction to bonds and bond marketsZero coupon bonds» Valuation» Yield-to-Maturity & Yield Curve» Spot Rates» Interest rate sensitivity – DVO1

Coupon bonds» Valuation» Arbitrage» Bond Prices Over Time» Yield Curve Revisited» Interest rate sensitivity – Duration & Immunization

Forward Rates

22


What is a Bond and What are its Features?

A bond is a security that obligates the issuer to make interest and principal payments to the holder on specified dates.» Maturity (or term)» Face value (or par): Notional amount used to compute interest payments» Coupon rate: Determines the amount of each coupon payment, expressed as an

APR

Bonds differ in several respects:» Repayment type» Issuer» Maturity» Security» Priority in case of default

Coupon Rate Face Value Number of Coupon Payments per Year

Coupon ×=


Repayment Schemes

Bonds with a balloon (or bullet) payment» Pure discount or zero-coupon bonds

– Pay no coupons prior to maturity.» Coupon bonds

– Pay a stated coupon at periodic intervals prior to maturity.» Floating-rate bonds

– Pay a variable coupon, reset periodically to a reference rate.

Bonds without a balloon payment» Perpetual bonds

– Pay a stated coupon at periodic intervals.» Annuity or self-amortizing bonds

– Pay a regular fixed amount each payment period.– Principal repaid over time rather than at maturity.

33


Who Issues Bonds?

US Government (Treasuries)» T-bills: 4,13,16-week maturity, zero coupon bonds» T-notes: 2,3,5,10 year, semi-annual coupon bonds» T-bonds: 20 & 30-year, semi-annual coupon bonds» TIPS: 5,10,20-year, semi-annual coupon bond, principal π-adjusted» Strips: Wide-ranging maturity, zero-coupon bond, IB-structured

Foreign GovernmentsMunicipalities» Maturities from one month to 40 years, semiannual coupons» Exempt from federal taxes (sometimes state and local as well).» Generally two types: Revenue bonds vs General Obligation bonds» Riskier than government bonds (e.g., Orange County)


Who Issues Bonds? (Cont.)

Agencies:» E.g. Government National Mortgage Association (Ginnie Mae),

Student Loan Marketing Association (Sallie Mae)» Most issues are mortgage-backed, pass-through securities.» Typically 30-year, monthly paying annuities mirroring underlying

securities» Prepayment risk.

Corporations» 4 types: notes, debentures, mortgage, asset-backed» ~30 year maturity, semi-annual coupon set to price at par» Additional features/provisions:

– Callable: right to retire all bonds on (or after) call date, for call price– convertible bonds– putable bonds

44


Bond Ratings

Moody’s S&P Quality of Issue Aaa AAA Highest quality. Very small risk of default.

Aa AA High quality. Small risk of default.

A A High-Medium quality. Strong attributes, but potentially

vulnerable. Baa BBB Medium quality. Currently adequate, but potentially

unreliable. Ba BB Some speculative element. Long-run prospects

questionable. B B Able to pay currently, but at risk of default in the future.

Caa CCC Poor quality. Clear danger of default.

Ca CC High speculative quality. May be in default.

C C Lowest rated. Poor prospects of repayment.

D - In default.


The US Bond Market – FlowsAmount ($bil.). Source: Flow of Funds Data 2005-2007

132.3104.494.5Consumer Credit

1417.5

53.6

195

307.3

2005

1397.1

213.4

177.3

183.7

2006

1053.2

314.1

214.6

237.5

2007

Mortgages

Corporate

Municipal

U.S. Gov.

Debt Instrument

Dollar volume of bonds traded daily is 10 times that of equity markets!Outstanding investment-grade dollar denominated debt is about $8.3 trillion (e.g., treasuries, agencies, corporate and MBSs

55


Zero Coupon Bonds(a.k.a. Pure Discount Bonds)

Notation Reminder:» Vn= Bn = Market price of the bond in period n» F = Face value» R= Annual percentage rate» m = compounding periods (annual m = 1, semiannual m = 2,…)» i = Effective periodic interest rate; i=R/m» T= Maturity (in years)» N = Number of compounding periods; N = T*m» r = discount rate

Two cash flows to buyer of a zero coupon bond (a.k.a. “zero”):» -V0 at time 0» F at time T

What is the price of a bond?

( ) ( )0 0 0 0 or 1 1T N

F FV B V Br i

⎛ ⎞= = = =⎜ ⎟

⎜ ⎟+ +⎝ ⎠


Zero Coupon Bond Examples

Value a 5 year, U.S. Treasury strip with face value of $1,000. The APR is 7.5% with quarterly compounding?» Approach 1: Using R (APR) and i (effective periodic rate)

» Approach 2: Using r (EAR)

» Approach 3: Using r (periodic discount rate)

?

?

?

66


Yield to Maturity

The Yield to Maturity (YTM) is the one discount rate that sets the present value of the promised bond payments equal to the current market price of the bond» Doesn’t this sound vaguely familiar…

Example: Zero-Coupon Bond

» But this is just the IRR since

( )

1/

00

11

T

T

F FV r YTM yVr⎛ ⎞

= ⇒ = − = =⎜ ⎟+ ⎝ ⎠

?

( )

1/

00

0 11

T

T

F FV IRR YTM yVIRR⎛ ⎞

= − ⇒ = − = =⎜ ⎟+ ⎝ ⎠


Yields for Different Maturities

Note: bonds of different maturities have different YTMs

77


Spot Rates, Term Structure, Yield Curve

A spot rate is the interest rate on a T-year loan that is to be made today» r1=5% indicates that the current rate for a one-year loan today is 5%.» r2=6% indicates that the current rate for a two-year loan today is 6%.» Etc.» Spot rate = YTM on default-free zero bonds.

The term structure of interest rates is the series of spot rates r1, r2, r3,…relating interest rates to investment termThe yield curve is just a plot of the term structure: interest rates against investment term (or maturity)

» Zero-Coupon Yield Curve: built from zero-coupon bond yields (STRIPS)» Coupon Yield Curve: built from coupon bond yields (Treasuries)» Corporate Yield Curve: built from corporate bond yields of similar risk (i.e.,

credit rating)


Term Structure of Risk-Free U.S. Interest Rates, January 2004, 2005, and 2006

88


Using the Yield Curve

We should discount each cash flow by its appropriate discount rate, governed by the timing of the cash flowExample: What is the present value of $100, 10 years from today (Use the term structure from January 2004)

Generally speaking, we must use the appropriate discount rate for each cash flow:

1 22

11 2

1 (1 ) (1 ) (1 )=

= + + + =+ + + +∑

NN N

N nnN n

C CC CPVr r r r

?


A Cautionary Note

All of our valuation formulas (e.g., perpetuity, annuity) assume a flat term structure.» I.e., there is only one discount rate for cash flows received at any point

in timeRecall:» Growing Annuity:

» Growing Perpetuity:

– “r” is implicitly assumed to be the same every period…

1 1 1 ( ) (1 )

NgPV C

r g r

⎛ ⎞⎛ ⎞+⎜ ⎟= × − ⎜ ⎟⎜ ⎟− +⎝ ⎠⎝ ⎠

( )

CPVr g

=−

99


Interest Rate SensitivityZero Coupon Bonds

Why do zero-coupon bond prices change?...Interest rates change!

The price of a zero-coupon bond maturing in one year from today with face value $100 and an APR of 10% is:

Example: Now imagine that immediately after you buy the bond, the interest rate increase to 15%. What is the price of the bond now

( )0 1 NFV

i=

+

( )0 1100 $90.91

1 0.10V = =

+

?


Characterizing the Price Rate Sensitivityof Zero Coupon Bonds

Consider the following 1, 2 and 10-year zero-coupon bonds, all with » F=$1,000» APR of R=10%, compounded annually.

$0

$200

$400

$600

$800

$1,000

$1,200

0.0% 5.0% 10.0% 15.0% 20.0% 25.0%

1-Year

2-Year10-Year

Note 4 things:1. Bond prices are

inversely related to IR

2. Fix the interest rate: Longer term bonds are less expensive

3. Longer term bonds are more sensitive to IR changes than short term bonds

4. The lower the IR, the more sensitive the price.

1010


Quantifying the Interest Rate Sensitivityof Zero Coupon Bonds – DV01

What’s the natural thing to do? Compute the derivative

» If we change the interest rate by a little (e.g., 0.0001 or 1 basis point) than multiplying this number by the derivative should tell me how much the price will change, all else equal (i.e., DV01 = Dollar Value of 1 Basis Point)

Alternatively, we can just compute the prices at two different interest rates and look at the difference: B0(i) – B0 (i+0.0001)

( )

( ) ( )

( )( ) ( )

0

10

220

2

1

1 0 (Negative slope in )

1 1 0 (Convex function of )

N

N

N

FVi

V FN i iiV FN N i ii

− +

− +

=+

∂⇒ = − + <

∂∂

⇒ = + + >∂


Valuing Coupon BondsAmortization Bonds

Consider an amortization bond maturing in two years with semiannual payments of $1,000. Assume that the APR is 10% with semiannual compoundingHow can we value this security?1. Brute force discounting

2. Recognize the stream of cash flows as an annuity

( ) ( ) ( ) ( )0 2 3 41000 1000 1000 1000 $3545.95

1 0.10 / 2 1 0.10 / 2 1 0.10 / 2 1 0.10 / 2V = + + + =

+ + + +

( )40

1000 1 (1 0.10 / 2) $3,545.950.10 / 2

V −= − + =

( ) ( ) ( ) ( )0 0.5 1 1.5 21000 1000 1000 1000 $3545.95

1 0.1025 1 0.1025 1 0.1025 1 0.1025V = + + + =

+ + + +

(i):

EAR (r):or

1111


Replication

Can we construct the same cash flows as our amortization bond using other securities?


A First Look at Arbitrage

What if the bond is selling for $3,500 in the market?

1212


Valuation of Straight Coupon BondExample

What is the market price of a U.S. Treasury bond that has a coupon rate of 9%, a face value of $1,000 and matures exactly 10 years from today if the interest rate is 10% compounded semiannually?

0 6 12 108 120Months

Cash Flows 45 45 45 1045

Timeline:

Present Value = Current Price = ?


Valuation of Straight Coupon BondGeneral Formula

What is the market price of a bond that has an annual coupon C, face value F and matures exactly T years from today if the required rate of return is R, with m-periodic compounding?» Coupon payment is: c = C/m» Effective periodic interest rate is: i = R/m» number of periods N = Tm

» Note the assumption of a flat term structure…

[ ] [ ]

( ) ⎥⎦

⎤⎢⎣

⎡+

+⎥⎦

⎤⎢⎣

⎡ +−⋅=

+=−

N

N

iF

iic

ZeroAnnuityV

1)1(1

0

1313


Relationship Between Coupon Bond Prices and Interest Rates

Bond prices are inversely related to interest rates (or yields).

A bond sells at par only if its interest rate equals the coupon rate.

» Most bonds set the coupon rate at origination to sell at par

A bond sells at a premium if its coupon rate is above the interest rate.

A bond sells at a discount if its coupon rate is below the interest rate.


The Effect of Time on Bond Prices

1414


YTM and Bond Price Fluctuations

Over Time


Yield to MaturityCoupon Bonds

Recall: The Yield to Maturity is the one discount rate that sets the present value of the promised bond payments equal to the current market price of the bondPrices are usually given from trade prices» need to infer interest rate that has been used

» This is not the annualized yield, which equals yield* = ( 1 + yield / m)m-1Typically must solve using a computer» E.g., IRR function in excel or your calculator since:

( ) ( )NN myieldF

myieldmyieldcB

/1/111

/ ++⎟⎟

⎠

⎞⎜⎜⎝

⎛

+−=

( ) ( )NN myieldF

myieldmyieldcB

/1/111

/ ++⎟⎟

⎠

⎞⎜⎜⎝

⎛

+−=

1515


The Yield Curve Revisited

Treasury Coupon-Paying Yield Curve» Often referred to as “the yield curve”» Same idea as the zero-coupon yield curve except we use the

yields from coupon paying bonds, as opposed to zero-coupon bonds.

– Treasury notes and bonds are semi-annual coupon paying bonds

» We often use On-the-Run Bonds to estimate the yields– On-the-Run Bonds are the most recently issued bonds


Interest Rate SensitivityDuration

The Duration of a security is the percent sensitivity of the price to a small parallel shift in the level of interest rates.

» A small uniform change dy across maturities might by 1 basis point.» Duration gives the proportionate decline in value associated with a rise

in yield» Negative sign is to cancel negative first derivative

Alternatively, given a duration DB of a security with price B, a uniform change in the level of interest rates brings about a change in value of

1B

dBDuration DB dy

= = −

Bd B D d y B= − × ×

1616


Duration of a Coupon Bond

The mathematical expression for Duration is:

which we can rearrange

( ) 1 1

1

1 1 1 1 / (1 / )N

n Nn

n

dB n c y m N F y mB dy B m

− − − −

=

⎡ ⎤− = ⋅ ⋅ + + ⋅ ⋅ +⎢ ⎥

⎣ ⎦∑

( ) ( )

( ) ( ) ( )

1

1

1

1Time in Years "Weight" on

until n payment n payment

1 / (1 / )1 /

1 /

th th

n NNn

n

Nn

n

c y mn N F y mD y mm B m B

PV c PV Fn Ny mm B m B

− −−

=

−

=

⎡ ⎤⋅ + ⋅ += + ⋅ + ⋅⎢ ⎥

⎢ ⎥⎣ ⎦⎡ ⎤⎢ ⎥⎢ ⎥= + ⋅ + ⋅⎢ ⎥⎢ ⎥⎢ ⎥⎣ ⎦

∑

∑


Duration of a Coupon BondExample

Compute the duration of a two-year, semi-annual, 10% coupon, par bond, with face value of $100.

1717


More on Duration

Duration is a linear operator: D(B1 + B2) = D(B1) + D(B2)» The duration of a portfolio of securities is the value-weighted sum of

the individual security durations» DVO1 is also a linear operator

Duration is a local measure» Based on slope of price-yield relation at a specific point» Based on a bond of fixed maturity but maturity declines over time

Duration of a zero is

( ) 11 / ND y mm

−= +


Duration MatchingExample

Bank of Philadelphia balance sheet (Figures in $billions, D=duration assuming flat spot rate curve)

Duration of liabilities =The problem:» Increases in interest rates will decrease value of liabilities by more than assets

because of duration mismatch.

Liabilities & Shareholders EquityAssets

$25 Total Liabilities (D = ?)25Total Assets (D = 1)$5 Shareholder Equity

$10 2-Year Notes (D = 1.77)$10 Commercial Paper (D = 0.48)

?

1818


Duration MatchingExample (Cont.)

What is the change in assets value when interest rates change uniformly

What is the change in liability value when interest rates change uniformly

We want our assets and liabilities to experience similar value changes when interest rates change, so set these two expressions to be equal and solve for DL (DA=1.0):

?

?

?


Duration MatchingExample (Cont.)

What fraction of the bank’s liabilities should be in CP and Notes in order to get a liability duration of 1.25

How much money should the bank hold in CP and Notes in order to get a liability duration of 1.25

How should the bank alter their liabilities to achieve this structure

?

?

?

1919


Forward Rates

A forward rate is a rate agreed upon today, for a loan that is to be made in the future. (Not necessarily equal to the future spot rate!)» f2,1=7% indicates that we could contract today to borrow money at 7%

for one year, starting two years from today. Example: Consider the following term structure

r1=5.00%, r2=5.75%, r3=6.00%» Consider two investment strategies:

1. Invest $100 for three years how much do we have?2. Invest $100 for two years, and invest the proceeds at the one-year forward

rate, two periods hence how much do we have?» When are these two payoffs equal? (i.e. what is the implied forward

rate?)


Forward Rates

Strategy #1: Invest $100 for three years how much do we have

Strategy #2: Invest $100 for two years and then reinvest the proceeds for another year at the one year forward rate, two periods hence how much do we have

When are these two payoffs equal? (i.e. what is the implied forward rate?)

?

?

?

2020


Arbitraging Forward RatesExample

What if the prevailing forward rate in the market is 7%, as opposed to what calculated in the previous slide?Step 1: Is there a mispricing and, if so, what is mispriced

Step 2: Is the forward loan cheap or expensive

Step 3: Given your answer to Step 2, what is the first step in taking advantage of the mispricing

?

?

?


Arbitraging Forward RatesExample

2121


General Forward Rate Relation

Forward rates are entirely determined by spot rates (and vice versa) by no arbitrage considerations.General Forward Rate Relation: (1+rn+t)n+t=(1+rn)n(1+fn,t)t

Think of this picture for intuition:

Time 0 1 2

(1+r2)2

(1+r3)3

(1+f2,1)

(1+f2,1)(1+f1,1)(1+r1)

(1+r1) (1+f1,2)2

3


Summary

Bonds can be valued by discounting their future cash flows Bond prices change inversely with yieldPrice response of bond to interest rates depends on term to maturity.» Works well for zero-coupon bond, but not for coupon bonds

Measure interest rate sensitivity using duration.The term structure implies terms for future borrowing:» Forward rates» Compare with expected future spot rates

bonds - finance departmentfinance.wharton.upenn.edu/~mrrobert/resources/teaching/corpfinu… · baa...

Documents