本研究探討公司提列商譽減損時的市場反應以及經理人認列商譽減損的動機。實證結果發現，在未控制盈餘宣告效果下，提列商譽減損公司的股價在減損宣告前公司存在正向股價異常報酬，在宣告日後則存在顯著負向的異常報酬。但在控制盈餘宣告效果後，商譽減損的訊息並不會提前反應，宣告前之正向異常報酬源自盈餘宣告正向效果，表示經理人會選擇在盈餘有好消息時宣告商譽減損。至於宣告日後，資產減損金額對累積異常報酬具有顯著解釋能力，減損比率愈高，則累積異常報酬愈差。在認列商譽減損的決定因素部分，本研究支持商譽減損的提列是除了報導因素，也存在經濟因素。

In this paper we examine the market reaction to goodwill impairment loss and the determinants of recognition of goodwill impairments. Positive pre-event abnormal returns and negative post-event abnormal returns are observed around the write-offs announcement. After controlling for the potential earnings announcement effects, we find that the pre-event abnormal returns are not significantly related to impairment losses. This implies that observed positive stock reaction before the announcement date is attributable to the good earnings news and managers tent to announce goodwill write-offs when earnings news is good. The post-event abnormal returns are significantly negatively related to impairment losses after controlling for earnings announcement effects. The regression results support the arguments that goodwill impairment announcements have negative impacts on stock returns and the information of goodwill write-offs does not leak before the announcement date. As to the determinants of recognition of goodwill impairments, the empirical evidence shows that goodwill impairment losses are associated with the loss of economic values of goodwill and the managers’ discretionary behaviors.

我國為了與國際會計準則IAS No. 36 Impairment of Assets接軌，會計研究發展基金會於2004年7月公布財務會計準則第35號公報《資產減損之會計處理準則》，第35號公報實施的目的在於降低資產帳面價值與實際價值之間的差距，以提升財務報導的透明度，但商譽價值的不確定性、經理人對商譽減損的高度裁量權、商譽會計處理與其他資產的差異，以及商譽減損認列頻率顯著較低，使得商譽減損的動機與股價效果與其他資產有所差異，應該單獨予以分析。 本研究的研究結果可提供主管機關與投資人了解商譽公報的效果，也延伸目前對商譽減損相關研究。本研究發現，商譽減損資訊大都是跟隨各季盈餘宣告一起釋放出，商譽減損的訊息事先無法被投資人預期到，以及經理人傾向於選擇在季盈餘有好消息時提列商譽減損，因此，商譽減損宣告前因為股價提前反應盈餘的好消息，會呈現正向反應，一旦公司宣告商譽減損後，股價會針對先前未預期到的減損宣告進行反向修正。因此，當公司擁有較高商譽資產，因為商譽本身價值較主觀，評價較困難，經理人在提列損失有更高的裁量權，投資人對於商譽減損較固定資產減損更不容易事先預期到，因此投資風險顯然較高。投資人不可忽視這方面的風險。

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