共同基金在國內已經發展三十餘年，已成為國人一項重要的投資理財工具。唯傳統的基金設計係以「定期定額」的方式來操作，而本研究目的在於設計一套「不定期定額逢低投資」的操作方式，並證實該方式的投資績效係顯著優於傳統的基金操作。具體而言，本研究以2011年1月至2015年12月合計五年之基金每日淨值歷史資料，藉以比較定期定額與不定期定額(實際策略為當台股加權指數跌幅大於前一日1.25%即自動進行定額投資)分別在一年期、三年前、五年期以及金融海嘯期間(2008年)的績效表現。調查結果證實，不定期定額的績效均顯著優於定期定額的表現。本研究的結論可以提供投信產業設計新穎的共同基金，以提供投資人差異化的理財策略選擇。本研究相信，「不定期定額逢低投資組合」相當適合資金較充裕的積極型投資者。 / Mutual funds have been developed in Taiwan for more than 30 years and are now an important investment and financial tools for the people. Nonetheless the practice of traditional funds was designed through “dollar-cost averaging” and the study intends to design a practice of “value averaging bargain investment” to prove that the investment performance of the practice is significantly better than the traditional funds practice. Specifically, this study selected five years of NAV information from January 2011 to December 2015 to compare the performance of dollar cost averaging and value averaging (actual strategy was automatic fixed-amount investment when Taiwan Stock Exchange Capitalization Weighted Stock Index dropped 1.25% lower than previous day) based on strategic investment holding periods of one year, three years, five years and during the financial crisis (2008). The result proved that the performance of value averaging was significantly better than dollar cost averaging. The conclusion of this study could provide differentiated fiscal strategy for investment trust industry to design new mutual funds for investors. The study states that “the combination of value averaging and bargain investment” is more suitable for active investors with sufficient funds.