The S&P 500 is the go-to index for a lot of people when they think about the "market return;" an important idea in finance. It's a portfolio of a large enough

The S&P 500 is the go-to index for a lot of people when they think about the "market return;" an important idea in finance. It's a portfolio of a large enough number of companies that the portfolio return converges pretty thoroughly to the market return. Not sure why the S&P 1000 isn't used as much, but using the S&P 500 is a convention. Why choose all companies with female CEOs from the S&P 1000? The S&P 500 as of last year had 26 female CEOs, and if I had to guess, I'd say that number is higher than it would have been in 2002. The portfolio of "S&P 500 companies with female CEOs as of 2002" wouldn't have been diversified enough to reliably converge to the "market return of companies with female CEOs" that they were trying to investigate.