Most of the papers that study the distributional and
fractal properties of financial instruments focus on stock prices or
foreign exchange rates. This typically leads to mixed results
concerning the distributions of log-returns and some multi-fractal
properties of exchange rates, stock prices, and regional
indices. This paper uses a well diversified world stock index as the
central object of analysis. Such index approximates the growth
optimal portfolio, which is demonstrated under the benchmark
approach, it is the ideal reference unit for studying basic
securities. When denominating this world index in units of a given
currency, one measures the movements of the currency against the
entire market. This provides a least disturbed observation of the
currency dynamics. In this manner, one can expect to disentangle,
e.g., the superposition of the two currencies involved in an
exchange rate. This benchmark approach to the empirical analysis of
financial data allows us to establish remarkable stylized
facts. Most important is the observation that the repeatedly
documented multi-fractal appearance of financial time series is very
weak and much less pronounced than the deviation of the mono-scaling
properties from Brownian-motion type scaling. The generalized Hurst exponent H(2)
assumes typical values between 0.55 and
0.6. Accordingly, autocorrelations of log-returns decay according to
a power law, and the quadratic variation vanishes when going to
vanishing observation time step size. Furthermore, one can identify
the Student t distribution as the log-return distribution of a
well-diversified world stock index for long time horizons when a
long enough data series is used for estimation.
The study of dependence properties, finally, reveals that jumps at daily
horizon originate primarily in the stock market while at 5min horizon they originate in the
foreign exchange market.
The principal message of the empirical analysis is that there is
evidence that a diffusion model without multi-scaling could
reasonably well model the dynamics of a broadly diversified world stock index.
PACS 89.65.Gh Economics; econophysics, financial markets, business and management - 89.75.Da Systems obeying scaling laws