Jensen’s alpha:
It
is developed by Michael Jensen in 1968. It helps to measure the risk
adjusted return of a security in relation to market return. It uses Capital
Asset Pricing Model. It tells about the extra
return earned by security in market index. It is also known as abnormal return
or alpha. Alpha can be positive and
negative. If it is negative then the portfolio return is less than the market
return. If it is positive than the portfolio return is more than market return.
The portfolio which has positive Jensen’s alpha is considers better for the
investment.
Formula:
αp = Rp
– [Rf + βp (Rm
– Rf)]
Where,
αp = Alpha of portfolio
Rp = Return of a portfolio
βp = Beta of a portfolio
Rm = Market return
Rf = Risk free rate of return
Advantages of
Jensen’s alpha:
·
It helps to select the portfolio which gives
excess return in relation to market return.
·
It helps to measure the performance of hedge
funds.
Disadvantages of
Jensen’s alpha:
·
It uses single factor model that is CAPM which
only considers the market risk.
·
It does not consider the unsystematic risk
related to firm specific.
Difference between Jensen’s
alpha and Treynor ratio: Both the treynor ratio and Jensen’s alpha is based
on systematic risk. But the treynor ratio uses beta for calculation while
Jensen’s alpha uses CAPM model.
Difference between
Jensen’s alpha and Sharpe ratio: The Jensen’s alpha is based on systematic
risk and uses CAPM model to calculate risk adjusted return in relation to
market risk. While the Sharpe ratio considers the total risk which includes
systematic risk and unsystematic risk. It uses standard deviation for total
risk.
Example: Find out
the Jensen’s alpha with the help of given information:
·
Stock A has expected return of 12% and risk free
rate is 3.6%. The market return is 14.5% and beta coefficient is 1.23.
Solution: αp
= Rp – [Rf + βp (Rm –
Rf)]
= 12 – [3.6 + 1.23 (14.5 – 3.6)]
= 12 – [3.6 + 1.23*10.9]
= 12 – [3.6 + 13.41]
= 12 – 17.01
= -5.01%
Example: Find out
which investment gives excess return from the given investment portfolio (with
the help of Jensen’s alpha formula).
Investment Portfolio
|
Expected rate of return
|
Beta
|
Market return
|
A
|
9.6%
|
1.02
|
10.2
|
B
|
11.0%
|
2.15
|
10.3
|
C
|
8.6%
|
0.56
|
7.0
|
D
|
11.3%
|
-0.88
|
11.0
|
The risk free rate for all the investment is 5%.
Solution: αp
= Rp – [Rf + βp (Rm –
Rf)]
Investment portfolio A:
= 9.6 – [5 + 1.02 (10.2 -5)]
= 9.6 – 10.30
= -0.7%
Investment portfolio B:
= 11 – [5 + 2.15 (10.3 – 5)]
= 11 – 16.4
= -5.4%
Investment portfolio C:
= 8.6 – [5 + 0.56 (7.0 – 5)]
= 8.6 – 6.12
= 2.48%
Investment portfolio D:
= 11.3 – [5 + -0.88 (11.0 – 5)]
= 11.3 – (-0.28)
= 11.58%
The investment portfolio C and D gives positive Jensen’s
alpha that is 2.58% and 11.58% respectively. But the investment portfolio D
gives higher Jensen’s alpha or return i.e. 11.58% over market return 11%. So, Investment
portfolio D is best option than investment portfolio C.
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