White Noise Process

A white noise process is a sequence of random variables that are uncorrelated, have a mean of zero, and possess a constant variance. In financial theory, the ideal efficient market is often modeled as a white noise process because price changes should be unpredictable and contain no exploitable patterns.

If the residuals of a statistical model are white noise, it indicates that the model has successfully captured all available information and that no further systematic patterns remain. Conversely, if residuals exhibit structure, it suggests the model is incomplete or that there is an opportunity for arbitrage.

Recognizing white noise is essential for model validation and ensuring that trading strategies are not based on random fluctuations.