The capital market is one of the alternative means to raise long-term funds from the public as an investor in supporting the development of a country. Market timing in the world of stock investment is known as an appropriate time or condition to be inside or outside of the market or it can be interpreted as an appropriate situation for investors to buy assets as well as to sell them. The purpose of this study was to determine the differences in returns that occurred on Monday to Friday on the trading of LQ45 company stock and to find out the Monday Effect and Weekend Effect on trading stocks of LQ45 companies. The type of data used is quantitative data. The data analysis techniques used in this study were one-sample t-test and the independent sample t-test. The results of data analysis of one sample t-test showed that there is a significant difference between the company's daily stock returns included in LQ-45 on trading days in one week on the Indonesia Stock Exchange. The results of the independent sample t-test revealed that there is a significant difference between Monday's stock returns and Friday's stock returns. Average stock return on Monday (0,000777619) i
