Overfitting
Overfitting occurs when a trading model is too closely tailored to historical data, capturing noise rather than genuine market patterns. This results in a model that performs exceptionally well on past data but fails to predict future performance.
It is one of the most common pitfalls in quantitative finance. Overfitting often happens when a model has too many parameters or is trained on an insufficient sample size.
To avoid this, traders use techniques like cross-validation and out-of-sample testing. It is critical to ensure that a model generalizes well to new, unseen market conditions.
A model that is overfitted is essentially useless for live trading, as it lacks the flexibility to adapt to changing market dynamics. Preventing overfitting is a key aspect of building a durable strategy.