This dissertation studies the reaction of trading behavior of investors, especially institutional investors, to the public information in Taiwan. Two kinds of public information are chosen in this dissertation. One is open-ending closed-end funds under the regulation set up by Taiwan authority. The other is the change of stocks in MSCI Taiwan Index that is decided by Morgan Stanley Capital International (MSCI), a well-known foreign institution in constructing various indices. Consistent with earlier studies using U.S. data, our results show that open-ending is a wealth-enhancing event for shareholders. We also provide evidence of the existence of noise traders in the closed-end fund market. The evidence is derived from the trading behavior of domestic institutional investors and small individual investors, who ignore price discounts when open-ending is imminent. The trading by noise traders impedes price adjustments to the discounts, and provides profit opportunities to arbitragers. Furthermore, we show that foreign investors gain considerable wealth, largely at the expense of domestic institutional investors and small individual investors, in the open-ending process. On average, their gains account for 30% of the total gains associated with open-ending, or NT$562 millions per case. On the issue of the change of stocks in MSCI Taiwan Index, we find that MSCI prefers to select the securities with good performance, high liquidity, and large firm size into MSCI Taiwan Index while tends to drop the securities with poor performance, lower liquidity, and small firm size from MSCI Taiwan Index. Besides, consistent with the previous studies, prices increase (decrease) significantly for stocks added to (deleted from) the MSCI Taiwan Index after the announcement date. As well as the deletions, the price decreases for unchanging stocks after the announcement date. However, there is no evidence to find that foreign investors have information advantage in MSCI news over domestic investors. Foreign investors increase (decrease) their holdings on stocks included in (excluded from) the MSCI Taiwan Index after the announcement date. Moreover, price pressure hypothesis is not supported. Visibility hypothesis, information content hypothesis, downward sloping demand curves hypothesis are supported. Finally, for additions and deletions, the market-adjusted returns are driven by the contemporaneous excess buy of foreign investors and the contemporaneous excess sells of domestic corporations and individuals.