認購權證已在台灣發行與交易已接近七年的歷史，提供了更多套利、投機與避險交易的機會給市場參與者，也同時增加資本市場之完整性。而由於認購權證提供持有者在一段期間內依照特定價格購買特定數量標的股票之權利，投資人可以根據其意願與看法於到期日前來決定是否進行履約。而權證投資人購買權證之權利金即是包含內含價值與投資人願意支付的時間價值兩部分。時間價值的多寡反應出投資人對於未來權證履約價格是否可以無限增加的看法。而在其他條件不變之下，距到期時間越久之權證的價值應是越高。不過，是否時間越接近到期日時，投資人對於時間價值的看法就會呈現單純線性下降的狀態，還是另外有其他的資訊內涵會影響投資人對於價值的看法，即為本研究所欲探討之主題。 本研究針對台灣市場中個股型認購權證不同時點之時間價值變化程度，與可能影響時間價值變化的因素進行分析，其研究結果如下： 1.研究樣本並非完全符合越接近到期日時間價值減少的現象越明顯的狀態，顯示時間價值的變化隱含著會有其他之因素影響投資願意支付金額的多寡。且部分權證的確曾發生短期內時間價值大幅衰減的現象。 2.權證之價內外程度、距到期日之遠近、相對交易量的多寡與標的股票是否為電子業，對時間價值減少均有顯著的影響。另外，距到期日之天數、權證相對成交量、標的股票所屬產業與市場是否處於多頭與否均顯著影響短期內發生時間價值大幅衰退之現象。 3.本研究發現目前無法利用權證發行條件的差異，來判斷此權證是否會在存續期間當中發生時間價值急速衰退的現象。 / Warrants has been traded in Taiwan for seven years, and provides more opportunities for participants to arbitrage, hedge and speculate in capital market. Warrant gives holders the right to buy stocks at certain price during a period of time. The premium (price) to long warrants is contained intrinsic value and time value. Other things being equal, the longer the time to expiration day, the higher the value of warrants, since there is larger probability for investors to get more return. However, would any other terms expect time to expiration affect the variations of time value, or if we can find some variables could provide other content of information and result the change of time value. This is what the study focus on. Followings are the results of this study: 1. There are not all thetas of warrants in this sample decreasing simply by the time to expiration. It seems to be other variables would cause the change of theta. Besides, some warrants had serious time-decay in a short period of time. 2. Intrinsic value, time to expiration, trading volume, whether underlying stock in electronic industry or not and the market condition all have obvious effects on decrease of time value and serious time-decay. 3. It is still impossible to use issue information to identify if this warrant will have time-decay in its life.

本篇論文使用馬可夫移轉變異數模型探討台指選擇權之買權的波動性。馬可夫移轉變異數模型將條件變異設定為可隨時間變動而改變，甚至移轉到不同區間上。樣本在不同區間下的平滑機率估計值有助於捕捉資料特性，實證結果顯示當樣本落在高波動率區間上時，會對應著重大事件的發生，例如2004年台灣319槍擊案、2006年全球股災、2008年金融海嘯等。當樣本落在低波動率區間上時，會對應著投資人傾向將台股指數的上漲或下跌視為超漲或超跌，而賦予台指選擇權之買權負的時間價值。 / This paper investigates the volatility of TAIEX Call Options using Markov-switching variance model. The Markov-switching variance model allows the conditional disturbances to change as time passes and even switch between different regimes. The estimation of smoothed probabilities under different regimes facilitates to capture the characteristics of data. The empirical result shows that the high volatility regime is related to extraordinary events, such as 319 shooting incident in 2004, the global stock market crash in 2006, and the Financial Crisis in 2008. When in low volatility regime, investors tend to treat rise or fall in TAIEX as overreactions and give TAIEX Call Options turning points of time values.

Straddles and strangles are common trading strategies introduced in a lot of textbooks and are widely used for option market participants. However, to our knowledge, we might not know how these trades should be designed, which trades are preferable, and how they are constructed in practice. Thus, we want to apply and discuss straddles and strangles as our trading strategies to the practical market. In our research paper, focusing on the time value and finding some profitable strategies are the two important concepts of our straddles and strangles. Being a sell side to earn the time value is our main goal. Although we may take higher risk, time value decay is helpful for us. The research focuses on straddles and strangles by using historical data of TAIEX futures and options. We use the closing price and settlement price as our trading price from data period January 2005 to December 2010. We also compare two different situations, holding positions to maturity and early offset condition, to our straddles and strangles. The findings show that the straddle strategies have positive earnings by holding positions to maturity, and 3 out of 4 strangle strategies have the same results. We can indeed earn the time value as a seller because time value decays quickly for the last seven days of the options contracts. After considering the early offset condition, the profitability of the ATM straddle and strangles become worse. We might easily fall into a trap in which the index futures price fluctuates greatly for a few days and comes back to the normal level on the settlement date. Therefore, we encounter loss due to selling low and buying high so that the trading performance is poor compared with the positions held to the end. Key words: Straddle Strategy, Strangle Strategy, Time Value, Settlement, Early Offset, TAIEX Options, TAIEX Futures