The linkage between the US and Korean stock markets: the case of NASDAQ, KOSDAQ, and the semiconductor stocks

This paper examines the interrelationship between stock prices in the US and Korea by applying the vector autoregression (VAR) model to the daily stock prices at three different level of aggregation – the national aggregate index level, the high-tech industry level and the semiconductor firm level – for the period of July 1996 through February 2001. The major findings of this study are as follows. First, the US stock market plays a leading role over the Korean market at every level of aggregation. The reverse direction of influence, from Korea to the US, was found to be minimal. Second, the evidence also suggests that the speed of transmission of innovation from the US to Korea is swift and finished for the most part within a 24-h period, although it takes three or four days to complete the whole process. Third, the influence of the US stock prices on Korean stock prices, which is measured by the innovation transmission using the impulse–response function (IRF) analysis, seems to be somewhat stronger in the composite national stock price indices and the tech-laden indices than high-tech firms. Fourth, at the firm level, the influence of Micron Technology on the leading semiconductor manufacturers in Korea is shown to be strong and persistent by passing about 34 percent of its innovations to the Korean firms within the three-day period. The impact of IBM and Intel on the Korean chip makers seems to be relatively smaller. Finally, stock prices in Korea, national stock price indices and individual high-tech stocks alike, have become much more responsive to innovations in the US stock prices after the 1997 financial crisis. The implications of the main findings in this paper are also discussed.