In: Accounting
The following table contains monthly returns for Cola Co. and Gas Co. for
2010
(the returns are shown in decimal form, i.e., 0.035 is 3.5%). Using this table and the fact that Cola Co. and Gas Co. have a correlation of
−0.0969,
calculate the volatility (standard deviation) of a portfolio that is
65%
invested in Cola Co. stock and
35%
invested in Gas Co. stock.
Month Cola Co Gas Co
Jan -0.0210 0.0280
Feb 0.0000 -0.0050
Mar -0.0200 -0.0180
Apr 0.0090 0.0280
May -0.0310 0.0840
Jun -0.0840 -0.0460
Jul -0.1190 0.0820
Aug -0.0160 0.0460
Sep 0.0550 0.0300
Oct -0.0110 0.0140
Nov -0.0380 0.0290
Dec -0.0220 0.0740
(Click the icon to view the monthly returns.)
Calculate the volatility by:
a.
Using the formula:
Var left parenthesis Upper R Subscript p right parenthesis equals w Subscript 1 Superscript 2 Baseline SD left parenthesis Upper R 1 right parenthesis squared plus w Subscript 2 Superscript 2 Baseline SD left parenthesis Upper R 2 right parenthesis plus 2 w 1 w 2 Corr left parenthesis Upper R 1 comma Upper R 2 right parenthesis SD left parenthesis Upper R 1 right parenthesis SD left parenthesis Upper R 2 right parenthesisVarRp=w21SDR12+w22SDR2+2w1w2CorrR1,R2SDR1SDR2.
b.
Calculating the monthly returns of the portfolio and computing its volatility directly.
c.
How do your results compare?
a.
Use the formula
Var left parenthesis Upper R Subscript p right parenthesis equals w Subscript 1 Superscript 2 Baseline SD left parenthesis Upper R 1 right parenthesis squared plus w Subscript 2 Superscript 2 Baseline SD left parenthesis Upper R 2 right parenthesis plus 2 w 1 w 2 Corr left parenthesis Upper R 1 comma Upper R 2 right parenthesis SD left parenthesis Upper R 1 right parenthesis SD left parenthesis Upper R 2 right parenthesisVarRp=w21SDR12+w22SDR2+2w1w2CorrR1,R2SDR1SDR2.
The volatility (standard deviation) of the portfolio is
nothing%.
(Round to two decimal places.)