台灣發行量加權股價指數在編製時並未調整現金股利的影響，不僅會低估實際的投資報酬率，以其作為標竿指標，在評估共同基金績效時，亦會產生標竿錯誤的問題。因此，本文將現金股利的再投資報酬納入，重新編製加權股價指數。實證結果發現，若自民國75年起調整現金股利之影響，則在民國89年10月31日時，股價指數由5544.18點調整為6419.83點，約增加1.16倍。以新指數重新衡量基金績效的結果，發現績效排名並無大幅度的改變，而且基金績效是否擊敗大盤的情形，受新指標的影響亦不大，此乃因近年來上市公司配息少，而且基金績效非常極端。但基於理論上的正確性，在計算投資報酬率及評估共同基金績效時，仍應以納入現金股利之加權股價指數為基礎，以降低因標竿指標錯誤所造成研究結果的偏誤，否則未來我國股票配息的情況及基金報酬率的特性若改變之後，以過去的方式評估績效將可能造成極大之偏差。 / The Taiwan Stock Exchange Market Weighted Index (TAIEX) is not adjusted for cash dividend. Since the TAIEX is commonly used for calculating the investment return of the Taiwan’s market and as the benchmark index for mutual fund performance evaluation, the investment return in Taiwan is underestimated and there is benchmark error in the evaluation of mutual fund performance. This paper adjusts the TAIEX by incorporating the effect of the reinvestment of cash dividend in the TAIEX. The beginning date of our adjustment is January 4, 1986. Since then until the end of October 2000, the adjusted TAIEX grew to 1.16 times of the unadjusted index. However, The mutual fund performance evaluated based on the adjusted index is insignificantly different from that based on the un-adjusted index. This is because mutual funds have extreme performance. Due to the small cash dividend paid out by the listed firms on the Taiwan Stock Exchange, the adjustment effect is not enough to overturn the evaluation of