可轉債發行對台灣企業資本結構與公司價值之影響

Abstract

本研究探討台灣企業發行不同類型公司債對資本結構調整速度與公司價值之影響。研究期間為 2008 年至 2024 年，樣本涵蓋台灣證券交易所上市公司，並排除金融產業、國營事業及政府機關。依據債券特性將公司債區分為一般公司債與可轉換公司債，並細分為具擔保與無擔保之四種類型。為減少內生性偏誤，本研究採用 Mahalanobis 配對法建立控制組，並運用逐步差異中的差異法 (Staggered Difference-in-Differences) 進行實證分析。 實證結果顯示台灣企業發行公司債調整其資本結構之現象並不顯著，透過資本結構調整進而影響公司價值之效果亦有限。此外，發行可轉換公司債並未顯示出其預期的效果，即通過其股債轉換的特性，避免直接發行普通股所帶來的負面資訊效應，同時降低純債務籌資可能引發的財務困難風險等，這些因素未能顯著地幫助企業在資本結構調整中獲得更大的靈活性。 進一步分析具擔保公司債亦或是無擔保公司債，即使高槓桿比率企業傾向於發行具擔保公司債，然而並未因擔保條款降低信用風險而在資本結構調整上具顯著改變，進而提升公司價值。

This study investigates the impact of issuing different types of corporate bonds on the speed of capital structure adjustment and firm value among Taiwanese enterprises. The research period covers 2008 to 2024, with a sample consisting of companies listed on the Taiwan Stock Exchange, excluding financial institutions, state-owned enterprises, and government agencies. Based on bond characteristics, corporate bonds are classified into straight bonds and convertible bonds, and further divided into four categories: secured and unsecured bonds. To mitigate endogeneity bias, this study employs the Mahalanobis matching method to construct a control group and applies the staggered difference-in-differences approach for empirical analysis. The empirical results show that the issuance of corporate bonds by Taiwanese firms does not significantly influence their capital structure adjustment, nor does it substantially affect firm value through such adjustment. Furthermore, the issuance of convertible bonds does not exhibit the anticipated effects, such as mitigating the negative information effect associated with direct equity issuance or reducing the risk of financial distress from pure debt financing. These factors do not significantly enhance a firm’s flexibility in capital structure adjustment. Further analysis also indicates that, although highly leveraged firms tend to issue secured bonds, the presence of collateral clauses does not significantly reduce credit risk in a manner that facilitates capital structure adjustment or leads to an improvement in firm value.