在國人愈來愈重視投資理財的今日，股票已成為全民熱烈參與的運動。國外的研究中發現，股票市場中常會存在追高殺低的情況，也就是報酬好的股票可能會有持續良好的表現。然而，此種報酬的持續現象是否也同樣存在於國內，這正是本研究所探討的主題之一。 　　此外，與盈餘相關訊息（如非預期盈餘、盈餘發佈日前後數日的異常報酬及分析師對盈餘預測的修正程度等）對未來股票報酬的影響程度究竟如何，則是本研究的另一個主題。 　　研究樣本取樣自民國82年至86年底之台灣上市公司股價及盈餘相關資訊進行實證分析。實證結果如下： 1. 在股票報酬持續效果研究上，股價有過度反應的現象，因而在六個月 後的報酬情況有回歸平均的情形，也就是說前六個月的報酬較佳的股票在六個月後的報酬將會較低。然而，一年後乃至於三年後過去報酬較好的股價仍然能有較好的報酬。可見在台股中股價仍然存在有延續的現象。 2. 有關非預期盈餘對未來報酬影響情況的研究部份，此一訊息的延續效果大約有二年期間，隨著各項與盈餘有關訊息的發佈，將使得非預期盈餘的幅度愈來愈小，終至不具影響力。 3. 盈餘發佈日前後的異常報酬因為僅以四天的股價異常報酬做為盈餘的替代指標，所含資訊內容有限，因而使得其影響效果存續期間非常地短暫。實證結果發現在六個月內具有持續效果，超過六個月後，這項訊息將不再具有影響能力。 4. 至於分析師對國內上市公司盈餘預測的實證研究中，我們發現如果分析師對於某一家公司的盈餘預測修正幅度愈大，其未來的股價報酬將愈不理想。 5. 綜合來說，股價的持續效果比盈餘訊息對股價報酬的影響效果更為明顯；而非預期盈餘是一項不錯的選股指標。結合過去六個月的股價報酬及非預期盈餘來選擇一、二年期的投資標的是一項很有效的選股方式。 目 錄 第一章 緒論 1 第一節 研究背景與動機 1 第二節 研究目的與重要性 2 第三節 研究架構 3 第二章 相關文獻探討 5 第一節 投資報酬之影響因素 5 第二節 價格的持續效果 6 第三節 盈餘對股價影響效果的持續性 8 第三章 研究方法 12 第一節 研究假設 12 第二節 研究期間、對象與資料來源 12 第三節 研究設計 13 第四節 研究流程 21 第四章 實證結果與分析 22 第一節 過去六個月報酬影響未來報酬程度分析 22 第二節 非預期盈餘的高低對未來報酬影響情況分析 28 第三節 累計異常報酬對未來報酬的影響效果分析 33 第四節 分析師修正盈餘預測幅度對股票未來報酬的影響研究 39 第五節 價格持續效果及盈餘持續效果比較分析 44 第五章 結論與建議 46 第一節 研究結論 46 第二節 後續研究建議 47 參考文獻 49 / Nowadays, people in Taiwan lay more emphases on investment and financing. They take part in investing in the stock market passionately. Research from overseas studies find that there is a phenomenon, “momentum effect” exists in the stock market. That is the reason why good-performance stocks could keep performing well. Whether the phenomenon exists in Taiwan, too? This is one of the topics of this research. 　　Moreover, how does the information about earnings, such as unexpected earnings, abcdrmal return around the earnings announcement and the changes of analysts’ forecasts on earnings, influence stock performance in the future? This is the other topic of this paper. 　　Samples from published corporate stock prices and information about earnings during 1993 to 1997 was used in this paper to do the research. The followings are five positive outcomes. 1. In the research of price momentum effect, the stock price had overreacted. It means that the mean-reversion condition existed in six months. However, the stock with good performance in the past six months would still have better return in one to three years. Therefore, we find that price momentum does exist in Taiwan stock market. 2. How did the effect of unexpected earnings on future return? We find that the effect of standardized unexpected earning would last for two years approximately. As the information of earnings was declared, the effect of unexpected earnings would drop. 3. The information was limited because of using abcdrmal return around announcement as the substitution of earnings. So, the effect of it would last for the short time. The positive outcome found that the abcdrmal return around earnings announcement did have influence in six mouths, but it took seldom effect over six months. 4. The last research was about the changes on analysts’ forecasts. We found that if the analyst made more correction on earnings forecast, the stock price would have poor performance in the future. 5. In general, the price momentum effect tends to be stronger and longer-lived than the earnings momentum effect. It would be an effective way to choose good-performance stocks in one to two years by the past-six-months performance and standardized unexpected earnings.