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We investigate the information link between Taiwan option and stock markets by using the multimarket sequential trade model developed by Easley, O¡¦Hara and Srinivas (1998). We test the condition if informed traders trade in the Taiwan option market by investigating the information role of TXO trading volume in Taiwan option market. The result shows that traders¡¦ activity in Taiwan option market is informative and TXO trading volumes have information content for future stock index movements. We show that the ¡§positive news¡¨ and ¡§negative news¡¨ option volumes can predict stock index over 45 minutes; what is different from the empirical result of Easley, O¡¦Hara and Srinivas (1998) is that in Taiwan option market even the standard call, put or all option volumes have predictive power for 25 minutes.

This thesis analyzes the timing issue related to informed trades under two different market frameworks. Firstly, the issue under the competitive market framework is analyzed. In financial market, a widely accepted assumption that competitive informed traders elect to trade immediately upon receiving their private information is now questioned. We propose a competitive rational expectations model to demonstrate that under some situations informed traders tend to trade late on their information because of the fear of adverse effect on prices from their informed trades. This phenomenon from delayed informed trades leads to the following: Price volatility will increase and adjacent price changes may exhibit positive serial correlation. Secondly, we turn to the alternative framework, i.e., a market microstructure framework. A large number of market microstructure models had already investigated the timing issue of informed trades. Most of them found that the competition among informed traders will make the informed traders incline to trade early than late on their information and the market therefore becomes more efficient. We develop a market microstructure model with competitive, risk averse informed traders and uninformed market makers. It is found that when the mass of informed traders is larger or the precision of private information is higher, the market becomes less efficient, that is, prices will delay revealing the private information and the market will postpone becoming liquid. Our results stand in contrast to those of other market microstructure models simply because informed traders in our model choose to trade late on their information. In conclusion, the thesis has proved that the timing to trade on their information is an important consideration for informed traders to determine their trading strategy maximizing their expected utility. Since this issue is seldom discussed in the previous literature, I deeply believe that there are many works to be done followed this work.

根據Easley, Kiefer, O’Hara and Paperman (1996)所發展的模型，我們可以對台灣證券交易所上市的股票進行訊息交易的研究。我們的結果顯示，交易越活絡的股票含有訊息交易的機率越低；而這與Easley, Kiefer, O’Hara and Paperman的研究結果一致；換句話說，紐約證券交易所與台灣證券交易所的股票對於訊息交易都有類似的特性。因此，根據研究結果，沒有訊息的投資人應該多去交易較活絡或交易量較大的股票，因為這些股票含有訊息交易的機率較低。 / Following the empirical model developed by Easley, Kiefer, O’Hara and Paperman (1996), we have investigated the information content of the stocks on the TSEC. Our result reveals that more liquid stocks have the lower risk of informed trade than do less liquid stocks and this is basically consistent with the finding of Easley, Kiefer, O’Hara and Paperman. Stocks on the NYSE and the TSEC have similar characteristics of informed trade. Therefore, for uninformed traders, it is better for them to trade stocks which are more liquid and have higher trading volume.