自上個世紀末以來，全球信貸市場發展迅速，債券及其相關衍生性金融商品之交易量逐年提高，如何有效管理償債能力等信用風險因素也成為近年來實務界重要課題。本研究延伸文獻Chen, Liao et al. (2011)，以利息保障倍數、財務槓桿比率作為償債能力代理變數，並加入債券評等分析三者間與公司債利差之關係。
本研究對債券評等進行延伸，探討債券評等為連續變數、設定債券評等虛擬變數與不同債券評等分組之下，2008年至2013年期間台灣公司償債能力是否與公司債利差有顯著關係。其後加入財務槓桿比率與債券評等的交叉相乘項，探討財務槓桿比率與債券評等交互作用是否會對公司債利差造成影響，最後以分量迴歸模型探討在特定分點下公司償債能力、債券評等對公司債利差之邊際效果，增強研究之穩固性。
實證分析結果顯示台灣於2008年至2013年期間中，公司之利息保障倍數與公司債利差呈顯著負相關，但財務槓桿比率與公司債利差有顯著負向關係，此結果較不符合一般經濟預期，不過公司若能適當運動其財務槓桿，則可有效降低公司債利差。此外債券評等雖然對公司債利差有顯著正向影響，然而結果顯示，評等最高級別之公司債其利差並非各評等中最小值，表示其信用風險未必最佳，且台灣公司資本結構與公司債利差之相關性具有隨分量高低改變而呈現反向變動之特性。

Due to the rapid development of global credit markets, trading volume of bonds and derivatives have been increased year by year since 1990s. How to manage credit risk, like solvency, has become an important issue in practical. This study extends the literature of Chen, Liao et al. (2011) by using interest coverage and financial leverage ratio as proxies of solvency, to explore the effects of solvency and bond rating on corporate bond yield spreads.
First, this study uses bond rating as continuous variables, dummy variables and rating group, then analyzes whether there are significant effects between Taiwanese corporates solvency on bond yield spreads from 2008 to 2013. Second, this paper adds a variable combining with financial leverage ratio and bond dummies to figure out if the interaction effect between financial ratio and bond could affect yield spreads. We use quantile regression to investigate the marginal effects between solvency and rating on bond yield spreads at specific quantiles on the last part of this study.
According to empirical results, from 2008 through 2013, interest coverage of Taiwanese companies negatively and significantly relates to bond yield spreads. On the other hand, financial leverage ratio positively and significantly relates to bond yield spreads, which is different from our expectation. However, if companies can appropriately use its financial leverage, it can reduce bond yield spreads effectively.
Bond rating positively and significantly relates to bond yield spreads, but the result shows that the highest rating doesn’t guarantee the minimum of yield spreads, which means its credit risk may not be the lowest. Finally, relationship between Taiwanese corporates’ capital structure and bond yield spreads varies from positive to negative when the yield spreads is from low quantile to high quantile.

中文部分
1. 利秀蘭、陳惠薇，(2005)，台灣景氣領先及同時指標之探討，經濟研究
2. 吳紫菱，(2008)，企業償債能力與信用風險關係之研究─KMV模型的再探討，財務管理學系研究所，高雄市，國立中山大學，碩士
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