過度自信管理者對股票併購意願及績效之影響

Abstract

過度自信管理者傾向於高估併購後的綜效，使得較願意進行併購活動；另一方面，過度自信管理者由於認為市場投資人低估其公司股票價值，使得具有融資偏好，偏好使用公司內部自有資金，而不願意以股票方式融資。研究以台灣1999年至2007年台灣上市櫃公司為樣本，探討過度自信管理者與公司進行股票支付型態之併購意願和併購的短期及長期績效報酬的關聯性。針對過度自信管理者之衡量指標乃參考Malmendier and Tate (2005a, 2008)，亦即，過度自信管理者傾向於自願性的增加對公司的持股，研究藉由觀察管理者的持股變化率來做判斷。 實證結果顯示，過度自信管理者相較於理性管理者，較不願意進行股票支付併購活動，且當公司內部現金流量充足時，其結果更為顯著。而在短期累積異常報酬，過度自信管理者所創造之報酬雖較理性管理者佳，不過未達顯著水準。另外，在一年期長期買進持有異常報酬，顯示過度自信管理者顯著較理性管理者帶來更大的併購效益；在兩年期的績效報酬，此結果並未顯著。

Overconfident managers have a characteristic of overestimating merge synergies. Therefore, the willingness to make merger and acquisition decisions increases. On the other hand, overconfident managers tend to believe the stock value of their own corporation is undervalued; they prefer internal capital to external capital market. This study examines the relation between managerial overconfidence and stock-payment merger and acquisition activities and the short-term and long-term post-M&A stock performances based on the companies listed on the Taiwan Stock Exchange and over-the-counter market from 1999 to 2007. It measures managerial overconfidence based on the changes in the managers' shareholdings. According to Malmendier and Tate (2005a, 2008), managers with a greater overconfidence tend to increase their shareholdings in order to make profits. The empirical result shows that overconfident managers are less likely to undertake stock-payment merger and acquisition activities and the relation between overconfident managers and merger and acquisition decision is stronger when the firm has abundant internal capital. Also managerial overconfidence in acquiring firms generates higher short-term cumulative abnormal return insignificantly. In addition, the result shows the one-year long-term post M&A performance is significantly higher for overconfident managers than for rational managers on average. However, for the two–year stock return performance, the result is insignificant.