SPY is based on the S&P 500 index, not futures. https://www.ssga.com/library-content/products/factsheets/etfs/us/factsheet-us-en-spy.pdf
Nope. SPY is based on the on the S&P Index not the Futures. Here is the SPY list of components from SPY's sponsor https://www.ssga.com/us/en/institutional/etfs/funds/spdr-sp-500-etf-trust-spy
%% Easy to get the 2 confused; last time I checked its 505 stocks also not 500.But I hope they never change the name to S&P 505 /LOL.