Comparative analysis of the use of deep and machine learning models for forecasting non-stationary financial time series using the example of the IMOEX index
Subject. Comparison of machine learning and deep learning architectures in the task of forecasting non-stationary financial time series using the example of the daily closing prices of the Moscow Exchange Index (IMOEX). Objectives. Critically evaluate modern architectures and demonstrate methodological pitfalls and statistical artifacts in predicting absolute prices, as well as evaluate the real predictive value of models, not just formal metrics. Methods. Based on the historical daily data of the IMOEX index (2010–2025), 20 signs were generated. The sample is split chronologically (80/10/10) to avoid data leakage. We compared the performance of 8 models (including LSTM, N-Linear, PatchTST, Chronos) using MAE, RMSE, and R2 metrics. Results. The hypothesis of a statistical artifact has been confirmed. The high R? (> 0.97) of most models is due to the fact that they simply repeat a consistent forecast (R2 = 0.976). The leaders are the fundamental Chronos model and the simple linear N-Linear (R2 = 0.98). They slightly exceeded the baseline forecast. PatchTST showed a low result (R2 = 0.32) due to conflicts in methodology and architecture. Conclusions. The value of the model for non–stationary series lies in its ability to bypass a strong persistent baseline. The opposite architectures showed the best results: the complex Chronos and the simple N-Linear. This proves that there is no single "best" solution. Quantum analytics needs both types of tools: fundamental models for accuracy (LFT) and linear models for speed (HFT).
Keywords: time series forecasting, deep learning, nonstationarity, statistical artifact, fundamental models
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