SPLG seeks to track the total return performance of the S&P 500, before fees and expenses. The fund is a part of the low-cost SPDR Portfolio ETF line up, a collection of core-exposure funds that track S&P indexes. S&P's index committee chooses at least 500 securities to represent the US large-cap spacenot necessarily the 500 largest by market cap, which can lead to some omissions of single names. The index considers sector balance as well as minimum size and liquidity in selecting securities for inclusion. The fund is rebalanced quarterly. Prior to November 16, 2017, SPLG tracked the Russell 1000 Index and traded under the ticker ONEK. Prior to January 24, 2020 the fund tracked SSgA Large Cap Index.