Dollar-Cost Averaging in Thailand’s Equity Index Mutual Fund and Day-of-the-Week Effect


  • Komwut Wissawapaisal College of Digital Innovation Technology Rangsit University, Thailand


Day-of-the-week effect, Dollar-cost averaging, Mutual fund


           This study aimed to address the question of which day of the week is optimal for purchasing mutual funds to maximize investment returns. It examined the day-of-the-week effect in investment and explores the concept of Dollar-Cost Averaging (DCA) in an equity mutual fund. The research focused on testing an index fund representing all listed publicly companies in the Thai stock market (SCBSET) over different time periods ranging from 5 years to 25 years. Continuous investments had been made in the mutual fund throughout these durations. The results indicated that there was no significant difference in long-term investment returns. However, it is noteworthy that purchasing mutual fund units on Mondays yields the highest returns, aligning with previous research suggesting that Mondays exhibit more negative price movements compared any other day of the week.  In this regards, dollar-cost averaging proves beneficial as investors have the opportunity to buy more units at lower costs on Monday. This results in a higher return on investment over the long term in comparison.  In addition, implementing DCA every Friday may lead to the lowest potential returns as the stock market tends to experience the highest upward adjustments on that day. For investors planning to sell their investments, Fridays could potentially offer the best returns.


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