This thesis examines whether foreign investors have an information advantage to local investors. By assuming the source of lead-lag relation comes from the difference in the speed of price adjustment to information and information advantages, the paper tests whether stocks with higher foreign ownership adjust faster to new information. This hypothesis is motivated by the common believe that foreign investors are better informed than local investors. Moreover, the paper also examines whether the difference in levels of foreign ownership and foreign limit can be claimed as the causes of cross-autocorrelation in stock returns, which has been found in Thailand. Data is obtained from January 2001 to December 2008 from the Stock Exchange of Thailand. This research performs three different models; the vector autoregressive (VAR) model, asymmetric regression and Dimson beta regression. This paper controls for the firm size. VAR shows that returns of low foreign ownership stocks lead returns of high foreign ownership stocks and returns of high foreign limit stocks lead returns of low foreign limit stocks. It means foreign investors do not have an information advantage over locals and degrees of foreign limit can delay information diffusion. The asymmetric regression presents that there is no difference of stocks' response to good and bad market-wide news. While Dimson market beta model shows that the slow adjustment to returns on market as a proxy of market-wide information causes the lead-lag relation between high and low foreign ownership stocks but doesn't cause the lead-lag relation between high and low foreign limit stocks. Both of foreign ownership and foreign limit cannot solely be claimed as the causes of the cross-autocorrelation in stock returns found in Thailand.