The study aims to investigate the existence of overconfidence bias in Vietnam, Thailand, and Singapore. This paper focuses on the Vietnam Stock Market and other two countries of ASEAN, namely Singapore and Thailand. Data was collected over the period from January 1, 2014 to December 31, 2018, daily returns for each of the securities. This paper uses the time series method, namely ADF test, Granger Causality and VAR approach to find evidences of the overconfidence effect in Vietnam in relation to some ASEAN markets. The results show similarities between the observed countries with slight variations, with focus on Vietnam market. In general concrete evidences of overconfidence were found in both Vietnamese and Singaporean markets, in which Singaporean investors show higher degree of overconfidence than Vietnamese investors. Overconfidence is not as clear in Thai market, however a direct causal link from increased returns to increased investor confidence was found. From the model deployed in the paper, there are reasons to conclude that Thai investors are under-confident. The findings of the study shed lights into the existence of overconfidence bias in Vietnam, Thailand, and Singapore on a comparative basis, provide more insights and implications for future research in this new and rising field of research.

Abstract
1. Introduction
2. Literatures Review
    2.1. Hypotheses
    2.2. Research Hypotheses
3. Data and Methodology
    3.1. Data Description
    3.2. Methodology
4. Empirical Results
    4.1. Overconfidence in Vietnam Stock Market
    4.2. Testing Overconfidence in Singapore StockMarket
    4.3. Testing Overconfidence in Thailand StockMarket
5. Discussions
6. Conclusions
References

• Dzung Tran Trung PHAN(Vice Dean, Faculty of Banking and Finance, Foreign Trade University) Corresponding Author.
• Van Hoang Thu LE(Foreign Trade University)
• Thanh Thi Ha NGUYEN(Faculty of Banking and Finance, Foreign Trade University)