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Learn · Risk and performance

Alpha

Alpha is a model-dependent estimate of return above or below the return predicted by a selected benchmark and risk model.

By Betta Signals Research Desk · Reviewed October 24, 2026

Plain-English definition: Alpha is a model-dependent estimate of return above or below the return predicted by a selected benchmark and risk model.[1]

How the term is used

Alpha is not simply any gain that beat an index. Its value depends on the benchmark, period, return frequency, risk model, fees, and treatment of distributions. Change those inputs and the estimate may change too.[1]

What to check before relying on it

A positive historical alpha does not prove skill or predict future outperformance. Short samples, omitted factors, survivorship bias, and data mining can all make the number look stronger than it is.

Example

An investment can beat the S&P 500 yet have negative model alpha if the model says its market exposure should have produced an even higher return.

BenchmarkBetaTotal return

Research last reviewed: October 24, 2026. This definition is educational and does not evaluate a particular security.

Sources

  1. OpenStax Principles of Finance: Applications in Performance Measurement — alpha and risk-adjusted performance concepts. Accessed October 24, 2026.