I don't have any experience trading index options on the S&P 500, but they seem to be (at least sometimes) displayed as "$SPX.X". I would've thought that SPX w

I don't have any experience trading index options on the S&P 500, but they seem to be (at least sometimes) displayed as "$SPX.X". I would've thought that SPX would be a natural shorthand, even though it is also the index itself. Also, I thought Joe/Jane Schmoe could just trade (some) index options with a regular broker, providing they have enough money.