Quote from kinggyppo:
es is the future contract from the link I sent you. It expires every few months, there is also spx contract known as the big due to the large tick size, this is a contract traded by institutions and deep pocket locals. spy is more like a stock and is what you should focus on. You can lose your house trading futures if you do not understand margin.
spy and its derivative options are extremely liquid. I have seen many times someone drop 5,000 lots and not move the bid one tick. You can't beat spy in terms of liquidity. Es mini is heavily traded by all the players, retail institutional etc. spy and es are two different animals.
http://seekingalpha.com/article/172876-driving-the-s-p-500-cash-index-spy-vs-es
nice, and for falcon, due to interest rates there is a +/- spread compared to cash that narrows to 0 by expiration.
