The number of market indexes now exceeds the number of U.S. stocks. Traditional ones such as the S&P 500 are collections of securities weighted by market value, and index funds mimic them as a low-cost way to deliver the market’s performance. Many new indexes are different: They include stocks based on custom criteria, such as having low volatility or high dividends.*
Demand. Many new benchmarks essentially repackage active investment strategies into indexes, says Eric Balchunas, senior exchange-traded fund analyst at Bloomberg Intelligence. They can then be tracked by so-called smart-beta ETFs, which fund companies are rolling out rapidly.