In 2022, the number of investors in the Indonesian stock market was approximately 8.1 million. The value has experienced fourfold growth compared to 2019. This surge occurred throughout the period of the epidemic. The aim of this financial research is to examine the difference before and during the COVID-19 pandemic on the monthly average return and variance/risk pattern of LQ45. On top of that, the research intends to investigate the presence of the sell-in-may-and-go-away (SIMAGA) effect and identify the optimal investment strategy for LQ45. The research methodology employed in this study is descriptive-comparative and utilizes a mathematical and statistical framework. The research sample comprises companies that were included in LQ45 from 1997 to 2022. The employed data analysis techniques encompass normality test, wilcoxon sum rank test, F-test, and investment strategy simulation. Results of this research indicate that there is no evidence of a negative effect of COVID-19 on the monthly return and risk/variance pattern of LQ45 and the SIMAGA phenomenon has not happened on LQ45 except in 2002. Additionally, SIABIN (sell-in-August-buy-in-November) has been identified as the best strategy for LQ45 so far. Moreover, the findings of this study can serve as a valuable resource for investors who allocate their investments towards LQ45 and help investors know the best strategy to buy shares. It is essential to allocate more attention towards monthly return variance, as it serves as a pivotal metric for gauging investment risk and significantly impacts overall returns.