亞洲商業銀行併購後的股票報酬之持續性研究

Abstract

此論文主要研究1997到2007年共293筆的亞洲商業銀行，併購後的長期績效表現是否持續。我們使用買進持有異常報酬法去計算銀行長期股價報酬。本研究顯示併購後36個月內的買進持有異常報酬呈現顯著的負效果，與短期股價CAAR呈現相同結果，我們的結論顯示若併購後未能在短期內產生併購綜效，那麼長期也很難達到。併購條件對於併購後的長期績效都呈現負相關，此結果與文獻相同。雖然文獻與本研究結果都顯示獲利能力ROA在長期績效都呈現顯著正相關，但是亞洲銀行併購績效仍舊因為區域與開發程度的不同，有些許的差異。此外，我們也推測因為亞洲市場並不像歐美市場有效率，所以未能達到顯著的併購績效表現。最後，本研究也談到亞洲金融風暴確實提高了金融併購案的案件數，但對併購銀行併購後的長期績效並無顯著的影響。

In this paper, we investigate the long-term post-merger performance of Asian acquiring bank by using 293 deals in the 1997-2007 periods. We use the Buy-and-Hold Abnormal Returns to analyze the long-term performance in stock returns of the acquirer. We find significant negative long-term abnormal returns rolling every 36-month after mergers, as well as the short-term abnormal returns, CAAR. It shows that if the Asian bank mergers cannot create the synergy in the short-term, it cannot create the synergy in the long-term, either. Consistent with the pervious literatures, the deal attribute is significant negative effects on the long-term performance. Although we find ROA is significant positive in the long-term performance, which is in line with the previous studies; there are some distinctions due to the different geography and the level of development. Ex: efficiency. Additionally, we speculate because the Asia market is not very efficiency, so our conclusion cannot consistent with the US and EU market. Eventually, this paper also finds that Asian financial Crisis brings the amount of mergers for a certainty, but it may not affect the performance of the acquirers after the merger.