Using Machine Learning to Forecast Portfolio Returns

Using Machine Learning to Forecast Portfolio Returns

2026-01-02

Machine learning is becoming a bigger part of the investment process, not because it is fashionable, but because markets now move faster and rely on far more information than traditional models were designed to handle. Prices, fundamentals, supply-chain data, sentiment, filings, even satellite images the data landscape is bigger and noisier than ever.  As a result, many teams are exploring ways to incorporate ML into their quantitative trading research, moving toward a more sophisticated era of Artificial Intelligence in trading that can handle today’s high-dimensional data.

Fintech - artistic impression.

Fintech – artistic impression. Image credit: pvproductions via Freepik, free license

Classic approaches like Markowitz’s Mean Variance Optimization still play an important role, but they rest on assumptions that often don’t hold during volatile market periods. Expected returns change, correlations break down, and non-linear effects become more relevant. Researchers such as Dr. Thomas Starke have pointed out that relying solely on these older frameworks can make portfolios slow to respond when regimes shift. This is exactly where machine learning can help: it offers more flexible tools for recognising patterns and adapting to new information.

Below is a practical, step-by-step view of how quantitative teams typically build an ML-driven forecasting and portfolio process.

Step 1: Build a Reliable Data Foundation

Any ML project in finance starts with data, and most of the work happens here. It’s not enough to collect price histories and fundamentals. You need well-aligned timestamps, clean series, and a clear idea of what the prediction target is. Mastering this ‘dirty work’ of data cleaning and feature engineering is often the first and most important step for anyone learning how to become a quantitative analyst. Many teams now incorporate additional sources such as:

Sentiment and News Data:
NLP models can scan articles, analyst notes, or filings and extract broad sentiment trends. With the rise of Large Language Models, many researchers are now building a ChatGPT trading strategy to extract alpha from earnings call nuances that traditional sentiment scanners might miss. These signals can be informative, but they are also noisy and usually work best when combined with other features.

Geospatial and Supply-Chain Signals:
Satellite images, shipping activity, and logistics data can provide insights into economic activity that don’t appear immediately in traditional financial statements.

Industry studies suggest that incorporating more timely, diverse datasets can help models react faster to changing market conditions. It doesn’t guarantee better forecasts, but it increases the amount of information available for decision-making.

Step 2: Choose Models That Fit the Forecasting Task

A core challenge with machine learning in portfolio management is selecting models that align with the forecast horizon, data depth, and trading constraints.

With clean, aligned data, the next step is selecting models that make sense for the problem. The right choice depends on the investment horizon, asset class, and the amount of data available.

Time-Series Models:
Recurrent networks such as LSTMs can capture longer-term dependencies in sequential data. They can be useful, but their performance is highly dependent on feature design and the chosen horizon. Many simple baselines, linear models, tree-based methods, even momentum filters still perform surprisingly well, so benchmarking is essential.

Reinforcement Learning:
RL is often explored for sequential decisions such as allocation or rebalancing. Markets, however, are far noisier and less predictable than the structured environments where RL has traditionally been successful. As a result, RL tools need heavy monitoring and strict constraints before being considered for production use.

For quants who want a structured path from theory to real implementation, an ai portfolio management course can help connect practical model selection with risk-aware workflows.

Step 3: Turn Forecasts into Portfolio Weights

A prediction only matters if it influences how a portfolio is allocated. This step involves converting model outputs into position sizes, while respecting liquidity, turnover, and risk constraints.

Non-Linear Allocation and Optimization:
Machine learning models can uncover relationships that traditional optimizers might miss. Techniques such as Genetic Algorithms (a form of heuristic optimization) can search wide combinations of weights, though they need careful tuning to avoid unstable allocations. Bayesian frameworks can help quantify uncertainty around expected returns and stress-test scenarios.

Rebalancing and Execution:
ML can help identify when positions should shift, but execution depends on transaction costs, market depth, and operational limits. Any strategy must account for slippage, spreads, and capacity constraints. These real-world frictions often determine whether a model performs well in live trading.

Early-warning indicators may sometimes capture rising market stress, but they should be treated as supporting tools not precise, standalone predictors. Market regimes change quickly, and no signal works consistently across cycles.

Step 4: Manage Model Risk and Maintain Transparency

Building a model is one thing; keeping it robust is another. Financial markets evolve, and ML models can degrade over time if not monitored carefully.

Overfitting and Drift:
Understanding how to backtest a trading strategy using machine learning requires moving beyond ‘one-shot’ tests; professional HFT companies rely on Walk-Forward Optimization to ensure their models haven’t simply memorized historical noise. This process of repeated validation windows and checks for information leakage is an essential part of a realistic workflow.

Interpretability and Governance:
Many ML approaches act like black boxes. For portfolio managers and risk teams, this is a challenge. Tools such as feature-attribution methods, surrogate models, and clear documentation help explain why a model behaves the way it does. These practices matter even more as regulatory expectations increase.

Conclusion

Machine learning is not replacing traditional quantitative techniques, it is expanding what is possible. When used carefully, ML helps researchers interpret high-dimensional data, recognise relationships that linear models miss, and respond more quickly to shifting market conditions. The real advantage comes from combining rigorous data work, cautious modelling, realistic execution assumptions, and strong governance.

For many, the ultimate goal is learning how to get a job at a hedge fund, which requires the ability to move from ‘black box’ AI to interpretable finance. For professionals looking to build these practical skills, choosing the best algorithmic trading course one that emphasizes ‘learn-by-coding’, is the most efficient way to master quantitative finance courses and bridge the gap to a live-ready implementation.

Using Machine Learning to Forecast Portfolio Returns
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