Beta weighting is a method used in portfolio analysis to assess and adjust for risk. It is a measure that compares the volatility of an asset or group of assets (such as a portfolio) to the volatility of a benchmark index, like the S&P 500.

Beta weighting provides an estimate of how much the value of a portfolio or asset might change with a 1% change in the value of the benchmark index. For instance, if a portfolio has a beta weight of 1.5, it is projected to change by 1.5% for every 1% change in the benchmark index.

This measurement is often used to determine the potential impact of market moves on a portfolio and to help make adjustments to reduce risk or increase exposure.