Market Efficiency and Long-range Dependence: Evidence from the Tehran Stock Market | Asian Journal of Economics, Finance and Management

In an efficient market, the price process must follow a random walk, and price changes must be random. The presence of short and long-range dependence in the stock price process rejects the random walk and resulting in market inefficiency. The main objective of this paper is to examine the Tehran exchange market inefficiency attributableto the presence of long-range dependence in the market.To do so, we study the time-varying long-range dependence in the Tehran Stock Exchange log-return process using financial econometrics models. We provide clear statistical evidence that the mean log-return price process of the Tehran exchange market is a non-stationary process with short rang memory. Our finding indicates that shocks in the volatility of the Tehran stock market decay more slowly than an exponential decay. The results provide strong evidence in rejecting the random walk and the market efficiency hypotheses in the Tehran stock exchange market.

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