S&P 500 as a tradable futures symbol: US500.f
This is a derivative contract that allows you to speculate on the price of the S&P 500 index. US500.f is therefore a continuous CFD futures symbol which price is based on the underlying asset. Of course, it should be noted here for the sake of argument that, since it is a CFD instrument, you do not become the owner of the US500.f when trading it. Rather you only speculate on its price.
Continuous in this case means that before each futures contract expires, there is an automatic rollover of the position. This will result in selling of old contracts and the buying of additional nearest futures contracts. These contracts are split by quarter, specifically March, June, September and December.