本研究旨在針對主併公司股東長期平均報酬爲負值的現象,以行爲公司財務觀點,提出新的解釋方式,驗證傲慢假說(hubris hypothesis)或過度自信假說(overconfidence hypothesis),是否也適用於台灣的併購市場。研究的樣本期間爲1993年到2003年,利用企業在併購事件日前的會計指標(相對ROA、相對ROE)及事件日前的相對股票報酬率,作爲衡量主併者是否傲慢自大。研究發現傲慢自大指標爲負值且具顯著性,顯示傲慢自大主併者,其併購後的異常報酬較低,且隨著事件窗口拉長負值愈大且顯著,顯示併購案並不能爲股東創造長期價值;而上述長、短期破壞股東價值的情況,可透過外部董事席次比率、外部大股東的存在,產生不同型式的調節效果。綜言之,主併公司外部治理機制可以抑制傲慢自大主併者的長、短期價值破壞行爲。研究中並進行健全性檢定,確認研究結論的健全性。
We examine the issue of hubris (over-confidence) about mergers and acquisitions (M&A) market in Taiwan. We measure past (excess) accounting performance and market return as a proxy for the likelihood of hubris. Using a panel dataset of acquirers in Taiwan from 1993 to 2003, we find that high hubris bidders have negative abnormal return subsequent to the M&A event, and the negative effect become more significant with longer event-window. We also examine the moderating effects of two sources of external monitoring (independent outside board members and external blockholders) on the relationship between CEO hubris/overconfidence and M&A performance. Results showed that outside blockholders and independent outside board play different moderating role. Our results are largely consistent with the hubris hypothesis where overconfident managers may engage in value-destroying M&A. We also perform several robustness tests to confirm the conclusion.