Return and volatility spillover effects among Vietnam, Singapore, and Thailand stock markets – a multivariate GARCH analysis

Abstract

In this study, we examine the own- and cross-effects of the return and volatility spillover between the equity markets of Vietnam and the two ASEAN countries, namely, Singapore and Thailand using monthly stock returns. In attempt to explore the level and magnitude of the spillover effects of the other markets on the Vietnamese stock market, we apply the multivariate generalized autoregressive conditional heteroskedasticity (MGARCH) framework. By utilizing the time-varying conditional volatility and conditional correlations between the stock markets which are resulted from estimation of the GARCH-BEKK model, the study also further shed light on the issues of portfolio diversification. In general, the study found the weak return linkages among the markets. Specifically, the study found no return linkages between Vietnam and Thailand and the unidirectional relationship between Vietnam and Singapore. However, the volatility linkages are highly significant for the three stock markets. It is found that the shock transmission relationship between emerging markets (i.e. Vietnam, Thailand) and developed market (i.e. Singapore) is unidirectional in direction to the emerging markets and the volatility transmission relationships between those are bidirectional. Besides, the variation in Vietnamese stock volatility is found to be more strongly influenced by the past own-shock effects than the past cross-shock effects. This indicates the low level of financial integration of Vietnam into the regional markets and implies the potential rooms for the international portfolio diversification gains. The findings on the return and volatility linkages have several important implications for both investors and policy makers. Firstly, because of the low correlations between the stock markets found, the investors can earn the gains from the portfolio diversification in the three markets. Secondly, the Vietnamese policy makers should be concerned with the harmful volatility spillover originating in the Thailand market that can affect the stability of the stock market. Thirdly, the implication is related to the monetary policy. The finding that the own shock transmissions have the strongest impact on the Vietnamese market’s volatility suggest that the policy makers should pay more attention to the domestic shocks so that the adequate and timely policy can be made.