Emerging insights: Unveiling market efficiency in Mongolia's transforming economy

The Efficient Market Hypothesis (EMH) posits that stock prices reflect all available information, preventing consistent outperformance in strong-form efficient markets. However, in inefficient markets, investors can achieve higher returns by exploiting informational advantages. This study evaluates whether the Mongolian capital market is weak-form efficient. Although the Mongolian Stock Exchange (MSE) has grown since its 1991 inception, it remains under-researched. Our analysis focuses on the MSE Top 20 Index's most frequent constituents between 2012 and 2023, assessing if their returns are independent and align with the random walk model—a characteristic of developed markets like the U.S. Using daily stock returns, we conducted statistical tests, including non-parametric (Kolmogorov-Smirnov for normality, Run test) and parametric analyses (autocorrelation under the random walk model). Results compellingly reject the random walk hypothesis, indicating weak-form inefficiency. This inefficiency implies a potential for investors to realize abnormal returns, especially through momentum-based strategies, challenging the EMH. Findings were consistent across three market cycles, enhancing robustness. Future research could apply advanced econometric models and compare results with other markets, offering deeper insights into the MSE's characteristics. This study opens new directions for strategic trading and market analysis within the Mongolian capital market.