本篇論文主為信用價差之時間序列研究，及其和違約相關性之間之互動關係研究。發現信用價差之水準值及波動性，都具有兩個明顯不同的狀態期間，另發現信用價差和違約相關系數之間存在正向關係，且信用價差之高低波動狀態和景氣呈現反向變動。 / In this paper, I empirically investigate the dynamics of credit spread with regime switching analysis. The finding exhibits evidence of two distinctive volatility as well as mean regimes for credit spread changes. Moreover, I document (1) that the volatility of credit spread positively corresponds to default correlation and (2) that lower (higher) volatility regimes corresponds to boom (bust) state of economy.

本文延伸Hull and White (2010)之跨池因子繫聯結構模型中違約相關性之描述，藉由納入Normal Inverse Gaussian分配並允許其帶有狀態轉換之特性，我們探究信用結構式商品清償順位結構中，影響次順位信用保護層(subordination level)之因素。我們以房屋抵押擔保貸款債權憑證(MBS CDO)為例，分析資產違約相關性、資產池微粒化程度、跨池違約相關性等結構性變數如何影響分券評等之合理性及風險特徵。本文的研究結果呼應Azzalini and Capitanio(2003)中所提及採用Gaussian因子繫聯結構模型之於評價信用結構商品的缺失。我們發現增進信用資產池損失分配的之厚尾性描述，得以改善高估或低估分券信用價差的情況。 / By incorporating the Normal Inverse Gaussian distribution and allowing for regime shifts in the correlation structure of the multi-pool factor copula of Hull and White (2010), in this thesis we explorer the factors constituenting the subordination levels of credit-structured products. Using MBS CDOs as an example, we examine how model-embedded variables, such as default correlation, reference-portfolio granularity, and cross-pool correlation, affect the risk profiles of MBS CDO tranches. Our numerical results echo the findings of Azzalini and Capitanio(2003) in that correlation structure obtained under the Gaussian factor copula model may be inadequate in capturing the fact-tailed characteristic of the reference-pool loss distribution, thus can result in over/under-estimation of CDO tranche spreads.

This paper emphasis on the importance of default correlation, and also illustrate how the concept is connected with the Basel Ⅱ framework’s intention. Moreover, the paper brought out the different methodologies used by practitioners to arrive at the default correlation calculation, namely, the dispute between asset correlation and equity correlation. Furthermore, based on the model proposed by Hamerle, Liebig, and Scheule (2004), a panel logit model is set up to capture the relationship between the default events and the risk components endured by the specific industry. The model is therefore used to test the applicability of such model using Taiwan’s banking industry data. The result is consistent with our expectation about including the macroeconomic variables which will help to explain the default events happened within the banking industry. But, to my surprise, the proposition about the contemporary systematic random risk effect seems to be insignificant and a fixed effect is suggested to be assumed instead.

本論文一共分為兩大主題，分別為匯率連結商品之評價與分析，及違約事件相關係數之估計。在結構型金融商品於市場上熱賣之後，金融業者紛紛投入財務工程領域，競相推出類似的產品。然而，自1971年世界各國開始實行浮動匯率制度之後，匯率風險較以往提高不少，因此各種不同設計的外匯衍生性商品開始不斷地問世。有鑑於此，本文希望藉由分析市場上的匯率商品：「新加坡華僑銀行一年期匯率連結結構型存款」，讓發行商和投資人了解結構型商品設計的要點與風險所在。在此商品中，本文利用多變數蒙地卡羅模擬法求出商品的近似價格，除了看發行商是否有利可尋之外，也提供發行商可行之避險策略。同時，本文也透過商品條款分析與情境分析，讓投資人了解其獲利所在與將面臨的風險。 / 由於近年來信用事件層出不窮，顯示出信用風險控管的重要性，信用衍生性商品也因而開始蓬勃發展。目前信用衍生性商品以信用違約交換為最大宗，擔保債權憑證(Collateralized Debt Obligations, CDO)為其次。由於一籃子信用衍生性商品和擔保債權憑證涉及多檔標的資產，在評價時，公司之間的違約相關係數是個重要因子，因此本文在另一個主題上，透過Robert Jarrow與Donald van Deventer(2005)提出的違約相關係數之估計方法，以簡約模型估計違約相關係數，利用台灣公司資料做實證分析，期許對連結多項標的資產之信用衍生性商品之評價有所幫助。