代表性偏誤促使投資人錯誤延伸現行趨勢，引起過度反應，然隨後一旦發現錯誤，導致價格修正反轉。本研究應用前後期月營收宣告之交互作用，來探討台灣股市投資人是否存在代表性偏誤。結果發現持續營收好消息後之平均報酬顯著低於持續營收壞消息後之平均報酬，即發現顯著之價格反轉。此證據支持代表性偏誤導致投資人對營收消息過度反應。此外，結果顯示未預期營收具有顯著的資訊內涵。

Representativeness bias can lead investors to incorrectly extrapolate existing trends and cause overreaction, which reverses at a later date once incorrect conclusions are proven false. This paper uses interactions between pre- and post-monthly sales announcements, to explore the existence of investors’ representativeness bias in the Taiwan stock market. I find that the average return following a series of good sales news is significantly lower than the average return following a series of bad sales news, i.e. the significant price reversals. This evidence supports that a representativeness bias leads investors to overreact to sales news. In addition, the results indicate significant information content of unexpected sales.

台灣上市(櫃)公司依證券交易法第36條規定應於每月10日以前，公告並申報上月營業收入金額，此一台灣特有之法令，提供投資大眾獲取更即時的公司營運情形，其公告頻率與時效性遠較季報或年報高。且就穩定經營的公司而言，營收與盈餘間應常維持穩定之關係，故月營收資訊廣為主管機關監督與投資者交易之參考依據。本研究除再次檢驗月營收宣告之資訊內涵外，並應用前後期月營收宣告之交互作用，來探討台灣股市投資人是否運用有限理性進行決策，導致其對營收消息過度反應或反應不足。若市場是有效率的，股價應完全充分反應營收宣告當時所揭露的資訊，但是當投資人對前期營收過度反應或反應不足時，則會影響股價對次期營收宣告之效果。在本文中，特別探討當投資人面對持續一連串營收好消息(或壞消息)時，其是否會誤判最近宣告之績效，將持續至次期或於次期反轉。 由本研究結果引申出的管理意涵為：一、月營收宣告對於股價具有顯著的資訊內涵，即股價對營收好消息產生正面的反應，以及股價對營收壞消息產生負面的反應，此亦顯示月營收訊息為台灣投資者進行股票評價之重要依據。二、台灣投資者面對一連串的營收好消息(或壞消息)後，會對未來的消息過度樂觀(或悲觀)，認為仍將持續為好消息(或壞消息)，過度反應致使股價高估(或低估)，隨後修正導致較低(或較高)的報酬。三、投資者若能掌握前期月營收趨勢，則可利用同時買進前期營收持續為壞消息組合與賣出前期營收持續為好消息組合之策略，於次期月營收宣告時，獲取顯著正的平均異常報酬；以及四、本文對前後期月營收宣告互動關係之深入剖析，其有助於瞭解台灣投資人如何處理月營收資訊，而將進一步瞭解市場對於月營收訊息的評價過程，並讓公司擬定出更具效率之訊息釋出策略，以及可作為投資者制定投資策略之參考依據。

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