Company Size Effect in the Stock Market of Thailand

Abstract

The outperformance of small capitalization companies over large capitalization companies is a well-known occurrence in developed markets (Gorn, 1962), (Jacobs, 1989) with (Banz, 1981) numerically showing that this effect on stocks in the New York Stock Exchange. This phenomenon is based on the idea that some company specific characteristics can have a statistically significant impact on stock performance. The existence, or otherwise of this effect in emerging markets has received less attention. Given the very different characteristics of emerging markets compared to mature markets like the US is not immediately evident that the same conclusions can be extrapolated. One of the immediate clear differences between emerging and mature markets is the depth with markets like the US having a large amount of listed companies as well as large average trading volumes. In fact, when this analysis has been repeated in some emerging markets, such as Sri Lanka, the results seem to indicate that there is no statistically appreciable difference between the return of small and large capitalization stocks (Macn, 2013). It should be noted that in the case of the Sri Lanka case there were only, at the time of the article, 25 listed companies, of which only 12 were included in the analysis. The specific case of the stock market of Thailand is analyzed in this paper. The results of this article seem to point towards the existence of a size effect, affecting stock performance, in the Thai stock market. Some articles covering emerging market as a whole as pointed towards the opposite results. Given the substantial differences among emerging markets countries it is perhaps a better approach to follow an individualized analysis, country per country, rather than treat it as a homogenous group.