公司治理、公司績效與投資策略

Corporate Governance, Firm Performance, and Investment Strategy

本研究建構一套適合台灣的公司治理評等指標，其中包括董監事會功能、股權結構以及介入股市情況等三項構面，藉以探討公司治理評等指標與公司績效之關聯性。本研究期間由1996年至2007年，扣除金融產業以及具有遺漏值之無效樣本，全體有效樣本為5,631個觀察值。研究結果顯示，不論是本研究最終建構之整合性公司治理評等指標，或是個別衡量構面（董監事會功能、股權結構以及介入股市情況），皆與公司績效呈現顯著正向關係。更重要的是本文發現個別公司治理構面變數對於公司績效的效果係包含於整合性公司治理評等指標之中，也就是個別公司治理構面變數都只是部分而無法完整衡量公司治理。整合性公司治理評等指標才能得到更完整的公司治理衡量。最後，本研究也證明投資人可以利用整合性公司治理評等指標的資訊，藉由買進公司治理強的公司股票並賣出公司治理弱的公司股票來獲得超額報酬。

This paper examines the relationship between corporate governance and firm performance. Besides the individual aspects (including the performance of the broad of directors, ownership structure, and involvement of capital markets) of governance characteristics, a composite corporate governance index is built. We show the firms under stronger governance experience better performance than those under weaker governance leading to a positive relation between corporate governance and firm performance. More importantly, we demonstrate that the effect of individual aspect of corporate governance on firm performance is subsumed in the composite corporate governance implying that the composite corporate governance index can proxy for corporate governance more precisely. Based on the composite corporate governance index, investors can earn abnormal return by longing firms with higher composite corporate governance index and shorting those with lower composite corporate governance index.