MORTGAGE-BACKED SECURITIES
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Transcript of MORTGAGE-BACKED SECURITIES
CHAPTER TWENTY
Practical Investment Management
Robert A. Strong
MORTGAGE-BACKED SECURITIES
South-Western / Thomson Learning © 2004 20 - 2
Outline
Mortgages Types Mortgage Mathematics Mortgage Risk
The Mortgage Backed Securities Market History Types of Securities
South-Western / Thomson Learning © 2004 20 - 3
Outline
Considerations in Pricing MortgageBacked Securities The Importance of Prepayment Rates The PSA Convention The Risks of MBS The Risk of Collateralized Mortgage Obligations The Risk of Stripped Mortgage Backed Securities
South-Western / Thomson Learning © 2004 20 - 4
Introduction
A mortgage is a loan with real estate as collateral. The lender, called the mortgage originator, often charges points as a fee for preparing and placing the mortgage.
It is quite common for the lender to sell the mortgage to another party.
The homeowner may be unaware of this, as the lender normally continues to be the mortgage servicer.
South-Western / Thomson Learning © 2004 20 - 5
Mortgages: Types
A fixed rate mortgage is one with payments based on a set interest rate that does not change.
An adjustable rate mortgage (ARM), also called a variable rate mortgage, has an interest rate that moves with some market interest rate, such as the Treasury bill rate.
Most ARMS have an annual reset to the interest rate. Many also have either a cap or a floor on the interest rate.
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Mortgages: Types
With a convertible mortgage, the borrower has the option to exchange it for a fixed rate at the prevailing ARM rate.
There are other mortgage arrangements: biweekly - payments are due every two weekssemi-monthly - payments are due two times
each monthgraduated payment - the monthly payments
increase following a predetermined schedule
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Mortgages: Types
shared appreciation - the borrower splits the rise in the value of the property with the lender in exchange for a reduced interest rate
reverse - the homeowner sells the property to a bank and receives monthly mortgage payments
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Mortgage Mathematics
There will be 30×12 = 360 monthly payments at a monthly interest rate of 8÷12 = 0.66667%
Example :
A bank approves a prospective homeowner for a 30-year, $100,000 mortgage at an 8% annual rate.
South-Western / Thomson Learning © 2004 20 - 9
Mortgage Mathematics
So:
36066667.0166667.0
1
66667.0
1000,100$ C
The monthly payment will be $733.76
For an annuity:
NRRR
C1
11value present
C = the monthly paymentR = the monthly interest rateN = the number of payments
where
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Mortgage Mathematics
If the borrower pays the bank $1,500 instead of $733.76 for the thirteenth payment, how will the amortization schedule be affected?
The bank considers the extra $766.24 the borrower paid a principal reduction, and the anticipated life of the loan will decrease.
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Mortgage Risk
Default risk is the risk that the borrower is unable or unwilling to repay the debt as agreed.
Interest rate risk is the risk that the general level of interest rates rises, such that the value of the mortgage’s cash flow stream declines.
Prepayment risk is the risk of an early payment of the original mortgage, such as when the home is sold or when the mortgage is refinanced at a lower rate.
South-Western / Thomson Learning © 2004 20 - 12
The Mortgage Backed Securities Market
The Federal National Mortgage Association (Fannie Mae), the Government National Mortgage Association (Ginnie Mae), & the Federal Home Loan Mortgage Corporation (Freddie Mac) support the US mortgage market by providing liquidity, buying conforming mortgages from banks across the country for resale elsewhere.
The term mortgage-backed securities refers to all products based on mortgage loans.
South-Western / Thomson Learning © 2004 20 - 13
Types of Securities
A pass-through security is a share of a poolof mortgages.
The holders receive a monthly check for theirportion of the scheduled principal and interest payments, plus their share of any prepayments that may occur.
Individual Individual Individual Mortgages Mortgages Mortgages
Mortgage Pool
Pass Through Security
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Pass-through securities may be issued and guaranteed by a government agency, or they may be private label.
Two types of derivative securities that spring from pass-through securities are collateralized mortgage obligations and stripped mortgage-backed securities.
Types of Securities
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Types of Securities
A collateralized mortgage obligation (CMO) isa security backed by a pool of mortgages and structured to transfer prepayment or interest rate risk from one group of security holders to another.
A given pool of mortgages backs two or moreclasses of securities called tranches.
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Types of Securities
Individual Individual Individual Mortgages Mortgages Mortgages
Mortgage Pool
A Tranche B Tranche C Tranche Other Tranches
Collateralized Mortgage Obligation
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Types of Securities
Insert Table 20-3 here.
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Types of Securities
With a sequential pay CMO, all the tranche holders receive monthly interest payments based on the principal amount outstanding in their tranche.
All principal payments go to the A tranche until the A tranche principal is completely returned. Only then will the investors in the next tranche begin to receive principal.
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Types of Securities
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Types of Securities
There are two types of stripped mortgage backed securities, or strips.
All the interest goes to the interest only (IO)security holders, while the entire principal goes to the principal only (PO) holders.
Individual Individual Individual Mortgages Mortgages Mortgages
Mortgage Pool
Interest Only Security Principal Only Security
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Considerations in Pricing Mortgage Backed Securities
The price risk of a MBS comes from the uncertainty about the timing of cash flows.
Prepayments can affect the realized return on a M BS substantially.
The offering memorandum for a M BS will state the assumptions used in estimating cash flows from the mortgage pool.
A benchmark assumption for the rate of mortgage prepayment is offered by the Public Securities Association (PSA).
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Constant Prepayment Rate
The standard PSA assumption is that a 30-year mortgage will see prepayments of 0.2% for the first month and that prepayments will increase by 0.2% for each of the next 29 months, after which they remain constant.
The 0.2% per month prepayment assumption is called 100% PSA.
Considerations in Pricing Mortgage Backed Securities
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Considerations in Pricing Mortgage Backed Securities
A MBS has default, interest rate, and prepayment risks.
Riskiness of Cash Flows
variable ratenon-callable
bond
fixed ratenon-callable
bond
principal onlysecurity
interestonly
security
$ AmountUnknown
TimingKnown
$ AmountKnown
TimingUnknown
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Declining interest rates will increase thevalue of a cash flow stream and will lead to prepayments.
If a mortgage pool sells at a discount,prepayments will increase the value of each of the tranches, with the higher duration tranches benefiting the most.
If the pool sells at a premium, thenprepayments will reduce everyone’s yield, with the effect most pronounced for the holders of the longer duration tranches.
The Risk of Collateralized Mortgage Obligations
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The Risk of Stripped Mortgage Backed Securities
Prepayment has different consequences forIO and PO strips. An extension of the mortgage decreases the value of the principal payments but increases the value of the interest payments.
Declining interest rates will increase thevalue of a series of known cash flows, as well as the likelihood of prepayment. Normally, the prepayment effect overwhelms the interest rate effect.
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The Risk of Stripped Mortgage Backed Securities
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The Risk of Stripped Mortgage Backed Securities
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The Risk of Stripped Mortgage Backed Securities
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The Risk of Stripped Mortgage Backed Securities
Insert Table 20-9 here.
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Review
Mortgages Types Mortgage Mathematics Mortgage Risk
The Mortgage Backed Securities Market History Types of Securities
South-Western / Thomson Learning © 2004 20 - 31
Review
Considerations in Pricing MortgageBacked Securities The Importance of Prepayment Rates The PSA Convention The Risks of MBS The Risk of Collateralized Mortgage Obligations The Risk of Stripped Mortgage Backed Securities