Stock investment strategy combining earnings power index and machine learning

•We proposed using machine-learning models for the relationship between factors of Earnings Power Index and excess returns.•We evaluated the model in predicting stock returns using the hedge portfolio test for the top and bottom 20% of observations.•Most portfolios, including EPI-related variables, presented positive returns regardless of the holding period.•The proposed approach can provide investors with a profitable mid-term strategy by estimating the probability of return changes. We propose an intermediate-term stock investment strategy based on fundamental analysis and machine learning. The approach uses predictors from the Earnings Power Index (EPI) as input variables derived from cross-sectional and time-series data from a company’s financial statements. The analytical methods of machine learning allow us to validate the link between financial factors and excess returns directly. We then select stocks for which returns are likely to increase at the time of the next disclosed financial statement. To verify the proposed approach’s usefulness, we use company data listed publicly on the Korean stock market from 2013 to 2019. We examine the profitability of trading strategy based on ten machine-learning techniques by forming long, short, and hedge portfolios with three different measures. As a result, most portfolios, including EPI-related variables, present positive returns regardless of the period. Especially, the neural network of the two layers with sigmoid function presents the best performance for the period of 3 months and 6 months, respectively. Our results show that incorporating machine learning is useful for mid-term stock investment. Further research into the possible convergence of financial statement analysis and machine-learning techniques is warranted.