第一節 結論
本文提出的DFPM-HWT 評價模型不僅包含 DFPM 解決非線性誤差的特性,
也具有Hull-White 利率結構與市場利率配合的優點。此評價模型具有以下優點:
在模型結構方面,離散型模型更能觀察市場利率和公司財報等離散時間訊息,而 且公司在償還負債、提早贖回負債或遭遇法律訴訟的時間點皆為離散時間而非連 續時間,運用離散時間點衡量負債價值比連續時間點來得更合理。在信用風險方 面,此評價模型的違約門檻可隨著利率的隨機變動做調整,比外生給定的違約門 檻更能合理地考慮公司違約的狀況,另外,放寬了回收率的限制,使此模型更能 符合現實債券市場上複雜的契約規則。在模型延伸方面,此評價模型更能處理資 產,包含離散跳躍因子與債券可贖回特性的評價,從第四章第二節可了解不同型 態的離散跳躍,此模型都可以合理評價;另外,也可以評價可贖回債券等複雜形 式的債券,解決Briys and Varenne (1997) 評價模型無法處理的債券型態。
第二節 後續研究建議
本文提出的DFPM-HWT 評價模型雖然可以處理許多現實情況下的負債評 價,但尚有許多方面能更加精進。提供以下兩方面做參考:
一、 負債評價方面
本文假設利率為Hull and White (1990) 提出的 extended Vasicek model (參考 (3.1.1)式),後續研究可以放寬利率波動度與均數復迴歸率為固定常數的限制,使 其模型更加完善。另外,本文評價的債券類型皆為固定債息的債券型態,後續研 究可以延伸探討浮動債息的公司債類型與可轉換債等債券型態的評價,讓其模型
更適合實務上的運用。
二、 衍生性商品評價方面
本文提出的DFPM-HWT 評價模型的建構理念,可延伸至其它種商品的價值 評價,例如具有障礙性質的彩虹選擇權即依據兩項隨機過程的標的物所構成,且 具有門檻限制的性質,即可運用此項建構理念來評價。
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