Arbitrage Pricing
Theory:
It is developed by Stephen Ross in 1976. It is a linear model and used
for estimating the asset price. It helps to determine the assets are overvalued
or undervalued. With the help of arbitrage investors can make a profit through
price differences of asset without any investment. There are many macro
economic factors (like inflation) and market and security specific factors
which affect the price of an assets and it is difficult to determine which factor consider or which
should not. There are some factors which
affect the price of security like-
·
Inflation
·
Gross Domestic Product
·
Interest rate
·
Market index
·
Investors confidence
·
Shift of yield curve etc.
To calculate the expected return on stock you have to consider these factors which affect the price of that stock.
To calculate the expected return on stock you have to consider these factors which affect the price of that stock.
If alpha is greater than zero then the expected return is
greater it means the security is overpriced. And if alpha is smaller than zero
it means expected return is smaller and security is under priced.
Arbitrage: It is
an activity in which any investor can buy a security from one market and
simultaneously sell it to other market for making risk less profit through price
discrimination of same security. The person who engages in this buying and
selling activity is known as arbitrager.
Formula:
E(r)i = rf + βi1 RP1 +
βi2
RP2 + βi3 RP3 +.... βin
RPn + ei
Where,
E(r)i = expected rate of return
rf = risk free rate
βi = beta sensitive to the associated factor
RP = risk premium
Ei= error term (unsystematic risk)
Assumptions:
·
All investors have homogeneous interest.
·
There is no arbitrage and if it is exist then
the investors take the advantages of it and turned into equilibrium state.
·
It has no transaction cost, no tax.
Advantages:
·
It includes more than one factor which affects
the price of security.
·
With the help of it determine the Is the
security overprice or under priced?
·
It helps to make arbitrage free market.
Disadvantages:
·
It does not specify the factors which affect the
price of the security.
·
It is difficult to identify the factors which
affect the price of security and expected rate of return.
Example: Find out
the expected return of portfolio A if the beta of portfolio is 1.52 and risk
free rate is 2%. Through research it has been analysed that there are 2 factors
which affect the portfolio A most is Inflation and interest rate. The beta of
inflation is 0.96 and risk premium is 5%. The beta and risk premium of interest
rate is 2.12 and 3% respectively.
Solution:
E(r)i = rf + βi1 RP1 +
βi2
RP2 + βi3 RP3 +.... βin
RPn + ei
= 2 + 0.96 + 5 + 2.12 + 3
= 13.08%
Example: Using
the arbitrage pricing theory find out the expected return if the risk free rate
is 2% from the following information:
Security
|
Factor
|
Beta (β1)
|
factor
|
Beta (β2)
|
A
|
2.33
|
2.10
|
0.98
|
0.78
|
B
|
1.3
|
1.26
|
1.25
|
1.95
|
C
|
0.65
|
1.45
|
2.56
|
0.89
|
Solution:
E(r)i = rf + βi1 f1 + βi2
f2 + βi3 f3 +.... βin
fn + ei
Security
|
A
|
B
|
C
|
Calculation
|
=2.1*2.33 + 0.78*0.98
= 4.90+0.76
= 5.66
|
= 1.26*1.3+ 1.95*1.25
=1.64+2.44
=4.08
|
= 1.45*0.65+ 0.89*2.56
=0.94+2.28
=3.22
|
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