Eduardo José Araújo Lima

Tests of the random walk hypothesis for equity markets: evidence from China, Hong Kong and Singapore

This study tests the random walk hypothesis for China, Hong Kong and Singapore. Using variance ratio tests, robust to heteroskedasticity and employing a recently developed bootstrap technique to customize percentiles for inference purposes it is found that Class A shares for Chinese stock exchanges and the Hong Kong equity markets are weak form efficient. However, Singapore and Class B shares for Chinese stock exchanges do not follow the random walk hypothesis, which suggests that liquidity and market capitalization may play a role in explaining results of weak form efficiency tests.

Market efficiency of Brazilian exchange rate: Evidence from variance ratio statistics and technical trading rules

This study utilizes the variance ratio test to examine the behavior of Brazilian exchange rate. We show that adjustments for multiple tests and a bootstrap methodology must be employed in order to avoid size distortions. We propose a block bootstrap scheme and show that it has much nicer properties than the traditional Chow-Denning [Chow, K.V., Denning, K.C., 1993. A simple multiple variance ratio test. Journal of Econometrics 58 (3), 385-401] multiple variance ratio tests. Overall, the method proposed in the paper provides evidence refuting the random walk behavior for the Brazilian exchange rate for long investment horizon, but consistent with the random walk hypothesis for short-run horizon. Additionally, we also test for the predictive power of variable moving average (VMA) and trading range break (TRB) technical rules and find evidence of forecasting ability for these rules. Nonetheless, the excess return that can be obtained from such rules is not significant, suggesting that such predictability is not economically significant.

The Effects of the Brazilian ADRs Program on Domestic Market Efficiency

This paper examines the impact on Brazilian stocks following American Depositary Receipts (ADRs) listing in the U.S. stock markets. Evidence suggests that a systematic change has taken place in the post-listing period as the multivariate variance ratio statistics have significantly decreased if compared to the pre-listing period, which indicates a move toward a more efficient domestic stock market. This empirical evidence is robust to the use of dollar and local currency-denominated returns. These results add to the literature that finds evidence on changes in domestic volatility and abnormal returns around listing dates.