本研究針對宣告日介於1999年至2005年的國內併購事件進行討論，觀察國內上市非金融類公司併購事件的宣告，是否能為主併公司的股東創造利益。本研究以兩種不同的角度衡量企業併購是否能為主併公司的股東創造利益：一、觀察併購宣告前後主併公司的股價是否出現累積異常報酬；二、觀察併購宣告前後主併公司的股東權益報酬率是否得到改善，亦即經營效率是否提升。研究結果發現主併公司的股價在短期確實出現累積異常報酬，但長期則出現零或負的累積異常報酬，此結果和多數國外市場的研究結果一致，顯示市場投資人對併購事件在短期有過度樂觀的反應。關於股東權益報酬率的改善，則以非電子類股的主併公司表現較佳，屬於電子類的主併公司則出現相對於同業，其股東權益報酬率有衰退的現象。

This study investigate the domestic merges took over between 1999 and 2005 in Taiwan, to observe whether merges create benefit for acquirers’ shareholders. We investigate whether merges create benefit for acquirers’ shareholders in two different point of view: First, whether there exists abnormal return of the acquirers’stock price. Second, whether the acquirers’ return on equity progress after merges. We find that theacquirers’ stock price indeed have positive abnormal return in the short-term, but zero or negative abnormal return in the long-term. This conclusion is consistent with most prior researches, and this result revealed the market investors’ overestimate of the merge synergy in the short-run. With regard to the progress of the return on equity,non-electronic industries outperform electronic industry. In fact, the progresses of return on equity of acquirers in electronic industry are worse than those of non-acquirers in electronic industry on average.