Beta measures how sensitive a stock's returns are to S&P 500 returns — β = 1.0 moves in line with the index, β > 1 amplifies moves, β < 1 dampens them.
Beta is estimated via OLS regression over a rolling 1-year window of daily returns. A beta of 1.5 tends to move about 50% more than the index in either direction; a beta below 1 dampens the index's moves. Beta is also unstable over time — a name can re-rate to a materially different beta after a business-model shift, which is why we recompute it on a rolling window rather than treating it as fixed.
Live example: AAPL's current beta is 0.00 — less volatile than the S&P 500 — a comparatively defensive profile. See the full AAPL forecast to see how this feeds its position-sizing recommendation.
Beta is an input to the quantum model's volatility calibration and to Kelly position sizing: a higher-beta name generally warrants a smaller position for the same dollar-risk budget, because its price swings — and stop-loss distance — tend to be larger.
The stock has historically moved about 50% more than the S&P 500 in either direction, amplifying both gains and losses.
In theory yes — a negative beta means a stock tends to move opposite the market — but this is rare among S&P 500 constituents.
Not necessarily. Low beta means low correlation with market-wide moves, but a stock can still carry large company-specific risk that beta alone doesn't capture.
AAPL analysis shows this metric in context, or browse all S&P 500 tickers.
Educational research only — not investment advice.