SPYX follows a subset of the S&P 500 index, divesting itself of certain energy-related firms. Companies owning specific fossil fuel reserves are removed, including those with exposure to thermal coal, non-metallurgical coal, conventional and unconventional oil, natural gas, shale gas, and other oils and gas. The resulting market cap-weighted roster forms the index. Excluding individual sectors or industries from the S&P 500 isnt new, and the fund offers a targeted exclusion (fossil fuel holders). Launched in December 2015, the fund has some sector tilts due to its Fossil Free stance. However, the coverage still provides solid US large-caps and slight mid-caps exposure. The index is rebalanced quarterly. Prior to Sep. 2, 2024, the fund tracked the S&P 500 Fossil Fuel Reserves Free Index.