Abstract

The paper calculates the approximate entropy using the algorithm proposed by Pincus (2008) on the daily closing price of ASEAN countries’ stock indices collected from the Datastream from January 2000 to December 2016. The approximate entropy is employed to measure the randomness of financial time series in ASEAN countries’ stock markets. The results on the whole data show that the fluctuation rate of return is much higher than the stock index and Singapore has the most stochastic time series, including stock index and its return. Indonesia’s stock index exhibits the lowest randomness as suggested by approximate entropy. After crisis, the randomness of time series in the Vietnam’s market is sharply enhanced and the Philippines has become a potential country for investors to seek arbitrage opportunities.