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題 名 | 選擇權風險值之衡量=Evaluating the Value-at-Risk of Option |
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作 者 | 張大成; 洪明欽; 劉志勇; | 書刊名 | 東吳經濟商學學報 |
卷 期 | 42 2003.09[民92.09] |
頁 次 | 頁105-134 |
分類號 | 562.1 |
關鍵詞 | 選擇權; 風險值; 極端值理論; Delta法; Delta-Gamma法; 蒙地卡羅法; Option; VaR; Extreme value theory; Delta; Delta-Gamma; Monte Carlo simulation; |
語 文 | 中文(Chinese) |
中文摘要 | 由於衍生性金融商品的高槓桿倍率,投資失利時所可能造成的損失非常可觀,因此各國金融機構的管理當局對衍生性金融商品的風險管理均相當的重視。有些衍生性金融商品 (如選擇權等) 與其基礎資產間具有非線性的報酬關係'這和一般線性報酬金融商品有很大的不同之處。傳統風險值模型面對此一複雜的金融市場時,很難精確地衡量市場風險。因此,如何找出此類衍生性金融商品更準確的風險值估計模型已成為一個重要的課題。本文比較了四種不同的風險值計算方法,並以台灣認購權證的資料進行實證分析,所得到的結論包括: (1) 權證報酬率的偏態及峰態係數均較其基礎資產為高, (2) Delta法在深價內權證之VaR估計有不錯的表現。但是在價平或價外的權證,所估計的VaR和真實的VaR間會有較大的誤差,而且越價外,差距越大, (3) Delta-Gamma法與Delta法所得到的結果並無明顯差異,其原因主要為實證資料中的Gamma值都相當小,對風險值的估計並無太大的影響, (4) 蒙地卡羅法具有最低的誤差效度,但是卻具有最高的風險值間距, (5) 極端值理論,不論是買方或賣方的部位,在價平型權證的準確度是所有模型中最好的。但是它在其他風險值模型都表現不錯的深價內權證土,準確性卻不高, (6) 權證在接近到期日時,若屬於價外,由於執行機會很小,其權值每天都接近零,因而其所求得的波動度 (及風險值) 也都接近零,進而導致大量的穿透次數發生。因此,在計算權證風險佳時,必須去除靠近到期日附近的資料,尤其是在深價外的權證更應如此。 |
英文摘要 | Unlike a linear risk, the exposures of options are nonlinear, because they respond non-constantly to changes in the value of the underlying instrument depending on whether they are the money (ITM), at-the-money (ATM), or out-of-the-money (OTM). As the commercial products are continuously renovated, new financial instruments are more complicated than ever. The first option (warrant) in Taiwan was issued in 1997. Since the authoritative organizations, such as BIS, recommended the Value-at-Risk (VaR) as a way to quantify marketing risks, VaR has recently become an important tool on market risk management. In this paper taking options data from Taiwan in our empirical study, we calculate the VaRs of options by using Delta, Delta-Gamma, Monte Carlo (MC) Simulation, and Extreme Value Theory(EVT) four methods, and the estimated VaR and predicting effectiveness of these models are compared. Our conclusions include: (1) Both skewness and kurtosis of option is significant higher than that of its underlying asset. (2) The performance of Delta method is good for deep ITM option, but not for the case of OTM option. (3) The evaluation results from Delta and Delta-Gamma are quite similar due to the near zero Gamma of options. (4) MC method has the lowest error efficiency and also the highest average range. (5) In the case of OTM or ATM option, EVT performs precisely, but not in the case of ITM option. (6) In the case of OTM option, as it approach to expiration date, the option values will be all near zero which induce to a very small estimated volatility (and also the VaR). In such case a false outlier (|real return|>estimated VaR) can occur easily. Hence, in calculating the VaR of option, the near expiration date returns should be removed from data, especially in the case of OTM. |
本系統中英文摘要資訊取自各篇刊載內容。