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Applications of state space models in finance

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2.2 Empirical properties 11<br />

p t<br />

R t (%)<br />

100 * R t (%) * R t (%)<br />

600<br />

500<br />

400<br />

300<br />

200<br />

100<br />

20<br />

10<br />

0<br />

−10<br />

−20<br />

200<br />

150<br />

100<br />

50<br />

0<br />

(a) Broad<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

p t<br />

R t (%)<br />

100 * R t (%) * R t (%)<br />

600<br />

500<br />

400<br />

300<br />

200<br />

100<br />

20<br />

10<br />

0<br />

−10<br />

−20<br />

500<br />

400<br />

300<br />

200<br />

100<br />

0<br />

(b) Insurance<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

p t<br />

R t (%)<br />

100 * R t (%) * R t (%)<br />

600<br />

500<br />

400<br />

300<br />

200<br />

100<br />

20<br />

10<br />

0<br />

−10<br />

−20<br />

200<br />

150<br />

100<br />

50<br />

0<br />

(c) Food & Beverages<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

1990 1995 2000 2005<br />

Figure 2.2: Summaries <strong>of</strong> the weekly returns on the (i) broad market, (ii) the Insurance<br />

sector and (iii) Food & Beverages. Summaries from top to bottom are time series <strong>of</strong><br />

orig<strong>in</strong>al prices, excess returns and squared excess returns.<br />

Another obvious property illustrated by the returns and squared return series is that<br />

weeks <strong>of</strong> large absolute movements are followed by weeks with the same characteristics.<br />

This phenomenon, commonly referred to as volatility cluster<strong>in</strong>g, can be particularly<br />

observed <strong>in</strong> the second half <strong>of</strong> the sample, which <strong>in</strong>cludes the Asian crisis (1997), the<br />

Russian debt crisis (1998) and the boom and bust <strong>of</strong> the dotcom bubble (1998–2003).<br />

Univariate descriptive statistics for the data and some standard test statistics, which<br />

are referred to <strong>in</strong> the follow<strong>in</strong>g subsections, are provided <strong>in</strong> Table 2.2. It can be seen<br />

that over the entire sample, the highest average weekly excess returns are <strong>of</strong>fered by<br />

Healthcare (0.17%), Oil & Gas (0.15%) and Utilities (0.15%). The lowest are realized<br />

for Automobiles & Parts (0.02%), Insurance (0.04%) and Retail (0.06%). The risk, as<br />

measured by the annualized standard deviation, ranges from 14.64% for the defensive<br />

Utilities to 30.45% for the high risk sector Technology.<br />

2.2.1 Thick tails<br />

The observed degree <strong>of</strong> kurtosis (ku) <strong>of</strong> market and sector returns reported <strong>in</strong> Table 2.2<br />

generally exceeds the normal value <strong>of</strong> three. Compared to a normal distribution, the<br />

peaks are higher and the tails are heavier, which reflects that large outly<strong>in</strong>g observations<br />

occur more <strong>of</strong>ten than can be expected under the assumption <strong>of</strong> normality. Accord<strong>in</strong>g

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