You're long a stock and want to strip out broad market risk. This tool regresses the stock's daily returns on SPY over the last ~2 years to estimate its beta, then tells you how much SPY to short so your position is market-neutral — and how much stock-specific risk still remains after the hedge.
Method: beta is the slope of the stock's daily returns regressed on SPY over the trailing ~2 years (cov / var). Shorting beta × your position in SPY offsets the market-driven part of your P&L; what's left is idiosyncratic, stock-specific risk, reported here as residual volatility. R² is the fraction of the stock's variance explained by the market, and correlation measures how tightly the two move together. Beta is estimated from historical data and is unstable — it drifts over time and can shift sharply in a crisis, so re-estimate and rebalance regularly. Volatilities are annualized with the square root of 252 trading days. Educational only - not investment advice.