Philippine E-Journals

The behavior of the stock market is widely regarded as unpredictable and erratic. However, erratic physical systems can be predicted to some extent by using appropriate models. In this study, the empirical behavior of the Philippine stock market was considered by using the daily historical values of the Philippine Stock Exchange Composite Index (PSEi) from 1993 to 2009. Analysis of the time series for the index, return, and acceleration suggests that the regularity of the dynamics of PSEi is more transparent when studied in terms of return rather than the index itself. Regularity in the probability distribution is however found only in the acceleration of the index. The empirical probability distributions of index, return, and acceleration suggest that simple random walk, random walk with drift, geometric Brownian motion, and Levy flight models do not apply to the Philippine stock market index. A study of autocorrelation however showed that the PSE index is independent and identically distributed. A study of the probability of the scaled return to origin shows a power law characteristic, indicative of fractal behavior. Phase space diagram analysis, however, revealed that the seemingly chaotic behaviour of the Philippine stock market is only approximate.