Applications of state space models in finance
Applications of state space models in finance
Applications of state space models in finance
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6.1 The unconditional beta <strong>in</strong> the CAPM 85<br />
for period t = 1, . . . , T . In the context <strong>of</strong> excess returns, αi is expected to be zero. Beta<br />
is def<strong>in</strong>ed as<br />
ˆβ OLS<br />
i<br />
= Cov(R0, Ri)<br />
. (6.4)<br />
V ar(R0)<br />
The error terms ɛi,t are assumed to be normally and <strong>in</strong>dependently distributed over time<br />
with zero mean and constant variance σ 2 i ; cf. Campbell et al. (1997, ¢ 5) who provide a<br />
review <strong>of</strong> the fundamental assumptions <strong>of</strong> the CAPM and their derivations.<br />
Table 6.1 summarizes the OLS results <strong>of</strong> the excess market model for the eighteen<br />
DJ Stoxx sector <strong>in</strong>dices estimated over the full sample. As expected, the <strong>in</strong>tercept<br />
is not different from zero at the 5% level for any sector. Therefore, if not mentioned<br />
otherwise, αi will be assumed to be zero <strong>in</strong> the follow<strong>in</strong>g. The estimated betas are all<br />
significant at the 1% level. Over the entire sample, the lowest beta was estimated for<br />
Table 6.1: OLS estimates <strong>of</strong> the excess market model.<br />
This table presents summary statistics for OLS estimation <strong>of</strong> the excess market model; ***<br />
means significance at the 1% level (**: 5%, *: 10%).<br />
Sector α × 10 2<br />
β R 2<br />
JB a<br />
Q(12) b<br />
LM(6) c<br />
Automobiles −0.09 1.15*** 0.64 168.43*** 11.75 53.38***<br />
Banks 0.03 1.06*** 0.82 2360.85*** 27.67*** 44.81***<br />
Basics 0.03 0.90*** 0.54 358.16*** 20.31* 171.64***<br />
Chemicals 0.00 0.91*** 0.66 500.13*** 19.48* 86.82***<br />
Construction −0.01 0.89*** 0.69 369.89*** 17.70 47.81***<br />
F<strong>in</strong>ancials −0.03 1.00*** 0.79 599.60*** 19.44* 79.92***<br />
Food 0.04 0.65*** 0.50 1485.44*** 55.02*** 184.76***<br />
Healthcare 0.09 0.78*** 0.50 324.62*** 12.25 58.89***<br />
Industrials −0.03 0.98*** 0.83 930.30*** 13.41 58.00***<br />
Insurance −0.09 1.27*** 0.77 1397.30*** 22.58** 74.91***<br />
Media −0.05 1.22*** 0.67 4508.10*** 51.20*** 74.82***<br />
Oil & Gas 0.07 0.76*** 0.43 279.22*** 36.97*** 114.59***<br />
Personal 0.00 0.91*** 0.74 1055.98*** 21.01** 95.63***<br />
Retail −0.05 0.95*** 0.61 964.95*** 19.48* 7.26<br />
Technology −0.08 1.49*** 0.66 1079.03*** 10.21 98.73***<br />
Telecom 0.01 1.19*** 0.64 464.12*** 24.50** 65.18***<br />
Travel −0.01 0.77*** 0.65 598.81*** 18.62* 38.80***<br />
Utilities 0.08* 0.69*** 0.62 38.38*** 15.19 36.20***<br />
a JB is the Jarque-Bera statistic for test<strong>in</strong>g normality. The relevant critical values at the<br />
95% (99%) level are 5.99 (9.21).<br />
b Q(12) is the test statistic <strong>of</strong> the Ljung-Box portmanteau test for the null hypothesis <strong>of</strong> no<br />
autocorrelation <strong>in</strong> the errors up to order 12. In case <strong>of</strong> OLS, the Q-statistic is asymptotically<br />
χ 2 distributed with 12 degrees <strong>of</strong> freedom. The critical values at the 95% (99%) level are 21.03<br />
(26.22).<br />
c LM(6) is the LM-statistic <strong>of</strong> Engle’s ARCH test for the null hypothesis <strong>of</strong> no ARCH effects<br />
up to order 6. The test statistic is asymptotically χ 2 distributed with 6 degrees <strong>of</strong> freedom.<br />
The relevant critical values at the 95% (99%) level are 12.59 (16.81).