公司治理與公開市場買回關聯性之研究

Abstract

公司治理之良窳足以左右董事會運作之成效，公司治理較好的企業，董事會之特質具有較高的獨立性、監督性與齊一性，且有較低的異動性與集權性。現行法律賦予董事會對於企業買回股份之主導權，故預期公司治理與股票買回決議有重大之關聯。 本研究以我國上市與上櫃公司2000至2005年為樣本期間，主要探討公司治理對於公開市場買回股票宣告、宣告效果以及企業宣告買回庫藏股、實際買回庫藏股與執行率有關決策之影響，其中執行率為實際買回庫藏股與宣告買回庫藏股數量之比值。研究結果發現公司治理較好之企業，董事會之決議較能符合全體股東之利益，不贊同有利於內部人但損害企業主體之買回股份行為，因此，宣告買回股份可能性較低、宣告次數亦較少。若公司治理愈好之企業，宣告時所產生之累積異常報酬愈大，顯示市場認為公司治理愈好之企業，所傳達之資訊可信度愈高，不實誇大宣告量以拉抬股價之意圖亦較低，傾向宣告較低之買回數量和金額比率。我國公司宣告買回股份時產生之正向股價效果降低公司執行買回之意願，股價漲幅較小之企業內，較易彰顯公司治理對執行率之正向影響力。

Corporate governance has a dramatic force to share repurchase decision since the board of directors are responsible for the direction and supervision of the company's business including the authorization of share repurchase programs. A well governed firm has a more independent, overseen, agreed and less changing, concentrated board structure. A poorly governed firm is just the opposite. According to share repurchase programs announced by companied trading in stock exchange market or over the counter from Aug. 2000 to Dec. 2005, this study investigates how corporate governance affects a wide range of open market repurchase activities in the probability of share repurchase announcements, share repurchase frequency, cumulative abnormal returns at announcement of the repurchases programs, announced target levels of repurchases, actual share repurchases and completion rate. Completion rate is the actual repurchases scaled by the target number of shares in the programs. The results indicate that well-governed firms which strongly defend against fraudulent announcements are less likely and frequent to announce share repurchase. They are associated with higher five-day abnormal returns surrounding announcement date, suggesting that governance structure proxies for the quality of management’s information. As managers in a well-governed firm are less likely to manipulate their firm’s stock price by exaggerating the announced size, governance structure is negatively related to the extent of repurchase offer. Although a strong positive reaction to the announcement lowers the firm’s demand for reacquiring securities, governance structure is positively related to completion rate in firms with lower stock returns two months following the announcement of the program.