Notes on scaling behaviour in financial and commodity markets Cian Tomas O'Criodain, Donal Holland, Misha Volkov and Khurshid Ahmad Trinity College, Dublin, Ireland Contents Abstract .......................................................................................................................... 2 Background .................................................................................................................... 2 Decomposing a time series .................................................................................... 2 The Promise of Wavelet Analysis .......................................................................... 3 Risk Analysis ............................................................................................................ 3 Statement of Problem: ................................................................................................ 3 Oil Future Contracts – High Frequency and Low frequency movements ...... 3 Oil Company Stocks ................................................................................................ 4 Method .......................................................................................................................... 4 Data and Case Studies ................................................................................................ 4 Decomposition of CL1 ............................................................................................. 4 Wavelet Variance ..................................................................................................... 4 Predicting CL1 .......................................................................................................... 4 Systemic Risk ........................................................................................................... 4 Afterword ....................................................................................................................... 4 References .................................................................................................................... 4 Notes on scaling behaviour in financial and commodity markets Cian Tomas O'Criodain, Donal Holland, Misha Volkov and Khurshid Ahmad Trinity College, Dublin, Ireland Abstract Oil shocks have had a profound effect on a global scale and yet oil prices show a periodicity that is remarkable in itself. Wavelet analysis has been used to decompose an oil futures contract (Cushing Light Oil – CL1) over a 10 year period covering wars, presidential elections, successful peace processes and ambitious economic and social programmes, and major changes in transportation technology. The decomposition is helps in computing wavelet variance at different scales and following Gencay et al.[23] leads to an estimate of systemic risk in oil future prices. We demonstrate a method that can be used to predict price of oil contracts over a limited horizon. Background One of the key properties of complex systems is scale invariance. Consider systems in financial and commodity markets for example: These systems are intrinsically nonlinear, have a multi-scale character in both space and time, and comprise components that show dynamic and interdependent relationships amongst each other: The systems, nevertheless, show a remarkable degree of stability characterised by cyclic change in the values of idiosyncratic variable and by the scale-invariant power law behaviour of control parameters, for instance, trading interval, or the size of an actor – firms large and small. The systemic stability can be ‘shocked’ into linear or non-linear trends for varying periods of time; this may produce volatility clusters, and there maybe longterm effects of the shock observed sometimes by the emergence of variance breaks in financial time series. The shock may be endogenous, caused by the complexity of interaction between constituent parts, or exogenous, caused by external or environmental stimuli. Decomposing a time series Wavelet analysis has ‘formalized old notions of decomposing a series into trend, seasonal and business cycle components’ [38]. The result of the analysis is the reexpression of a highly correlated time series in terms of the combinations of the uncorrelated wavelet coefficients [12][32][36]. These coefficients are associated with oscillations of different periods. In economics and finance the analysis of the raw time series at different scales can be used with some degree of success: (a) to deseasonalise and detrend raw foreign exchange data [21] [39]; (b) to study the scaling behaviour of economic indices [33]; (c) to conduct (Granger-) causality tests of different macroeconomic variables like money supply and real economy variables output [22] which shows no conclusive indication of causality at the raw data level but clear indication of causal connection between the variables at finer scales; (d) to investigate heterogeneous trading in commodity markets and the effect of other financial instrument on the prices [11] (e) to evaluate risk using multiscale beta estimation [23]. Wavelets have been used to test for the onset of trends [24], for stationarity [44], and for predicting the behaviour of financial markets [40] or as a preprocessor of time series for input to fuzzy logic-based prediction system[37]. Note that the wavelet-based approach is similar in spirit to the well-known ARCH and GARCH models [4][5][14][15][43] However, unlike the approach adapted in (G)ARCH models, the wavelet approach breaks down each volatile time series into several time series of very high to very low volatility: these time series can then be studied and interpreted separately. This study appears to the discovery of newer relationships and insights in the analysed data, which are not afforded by the GARCH and ARCH models [39]. The Promise of Wavelet Analysis The potential of multiscale wavelet decompositions in providing new insights in subjects as diverse as hydrology, astronomy, physics and geology, suggests the analysis of economic and financial data will perhaps benefit from wavelet analysis [36]. The roots of the wavelet analysis lie within filtering methods that deal with the identification and extraction of certain features (e.g., trends, seasonalities) from a time series, which are important in terms of modelling and inference. Traditionally, filters in economics and finance are used to extract components of a time series such as trends, business cycles, seasonalities, and noise. Two most commonly used methods of decomposition of a macroeconomic time series are the Beveridge-Nelson procedure [1] and Hodrick-Prescott filter [27]. Canova critically evaluated a set of popular filters used in detrending macroeconomic time series and showed that different detrending methods provide different stylised facts of the U.S. business cycle [7][8]. Burnside claimed that preferring a commonly used filtering method in macroeconomic analysis does not induce any lack of power [6]. Niemira and Klein studied forecasting financial and economic cycles in general [35], and Weigend and Gerschenfeld investigated time series prediction in natural and physical phenomena [45]. Kaiser and Maraval [28], and Diebold and Rudebusch [13] contained a detailed analysis of business cycle measurements and forecasts. Risk Analysis Financial time series do not vary in isolation from one another and their movements are indeed correlated [25]. The capital asset pricing model (CAPM), a tenet of modern financial economics, provides a method to quantify correlations amongst stock prices with a statistic called systematic risk or beta [41][30][29]. The CAPM essentially works on the principle that the expected return of a particular asset is dependent upon the total risk involved in holding that asset: that is, the average return of high beta stocks is higher than the average return of low beta stocks and that this relationship is roughly linear [3][18]. Again, recognizing the effect of time-scale on the beta or risk of an asset, several researchers have studied the stability of beta over different time horizons [26][20][2]. Since, wavelet analysis is a natural tool for studying the timescale properties of time series, its application for the calculation of betas or systematic risks at various time horizons within a CAPM framework are eminent. Gencay et al. provide a comprehensive wavelet-based methodology to calculate systematic risk at various time-scales and show that the relationship between the return of a portfolio and its beta becomes stronger as the time-scale increases [23]. This offers newer research avenues for assessing the risk and value of different cash flows in financial markets. In SCALES, we want to study the risk-return tradeoffs at different timescales and want to investigate their relationship with market sentiment. 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