從公司治理觀點探討股票購回宣告效果與執行

公司治理是所有者對經營者的一種監督與制衡機制，由董事會與管理高層制定一整套制度，共同尋求公司與股東利益最大化。過去許多文獻贊同公司治理存在的監督效果，可以有效解決代理問題。本研究擬以股票購回政策為例，首先檢測公司治理與股票購回宣告效果的關係。再者，考量到公司未必依計畫行事，本研究進一步檢測公司治理與購回股票執行成果的關係。實證結果顯示，公司治理對股票購回宣告效果存在顯著正向影響，亦即公司治理愈佳則股票購回宣告效果愈大。區分組別後，高度公司治理的宣告效果，顯著優於低度公司治理。在執行成果的檢測方面，當公司規模愈小、負債比率愈高、電子產業與買回目的是維護股東權益者，有較高執行率。但是，公司治理並無法解釋執行率。

關鍵字

股票購回；公司治理指標；執行率；異常報酬；單因子變異數法

並列摘要

Corporate governance is a checks-and-balances supervision mechanism exerted by corporate ownerson corporate managers. Together with the top management, boards of directors develop management systems to maximise the interests of their companies and shareholders. Several studies contend that the supervision effect of corporate governance offers an effective solution to the agency problem. As exemplified by the stock repurchase policy, this study first investigated the relationship between corporate governance and the announcement effect of stock repurchase. Considering companies do not always act as planned, this study further analysed the relationship between corporate governance and the execution results of stock repurchase. The empirical results show that corporate governance was significantly and positively correlated with the announcement effect of stock repurchase： specifically, the better the quality of corporate governance, the more significant the announcement effect of stock repurchase. The sampled companies were classified based on the level of corporate governance. Companies with a high level of corporate governance witnessed a more significant announcement effect of stock repurchase than those with a low level of corporate governance. Regarding the execution results of stock repurchase, the rate of execution was more likely to be high if: 1) the corporate scale was small; 2) the debt ratio was high; 3) the companieswere engaged in the electronic industry; and 4) stock repurchase was intended to maintain the interests of shareholders. However, corporate governance could not account for the rate of execution.