found this from a google search, first result:
http://www.usafutures.com/eminisp500.htm
Advantages of Trading Mini S&P 500 Futures and Options
Trading Mini S&P 500 futures and options offers investors several distinct advantages:
# Exposure -- Investors can have exposure to the U.S. stock market via the world's leading stock index. Although there are many indexes, some very popular, the S&P 500 has the most closely watched, actively traded and liquid of all futures products based on a stock index.
# Affordability -- The enormous appeal of the standard S&P 500 futures has caused the contract to grow beyond the reach of many investors. New Mini S&P 500 contracts allow investors to trade this benchmark index at a fraction of the cost. Mini S&P 500 futures will require much less margin than the standard S&P 500 futures.
# Opportunity -- These new contracts provide a variety of investment opportunities, such as: increasing or hedging portfolio exposure; spreading against other CME index products such as the S&P 500, Nasdaq 100, Russell 2000 and/or S&P MidCap 400, a cost-efficient way to benefit from rising or falling equity markets.
# Integrity -- CME customers and members are protected from default on futures and options contracts by the Exchange's sophisticated risk management and surveillance techniques. The CME Clearing House acts as the guarantor to each of its clearing members, thus ensuring the integrity of all trades. The CME system has proven to be outstandingly effective, even under the most stressful market conditions.
The CME is The Index Exchange, with more than 95% market share of all domestically traded stock index futures and options on futures. Open interest in the CME's index complex totals in excess of $93 billion, making it the world's most liquid trading environment for stock index products.
What, Exactly, Are Mini S&P 500 Futures?
Mini S&P 500 futures are legally binding agreements to buy or sell the cash value of the S&P 500 Index at a specific future date. The contracts are valued at $50 x the futures price. For example, if the Mini S&P 500 futures price is at 920.00, the value of the contract is $46,000 ($50 x 920.00).
The minimum price movement of the futures or options contracts is called a "tick." The tick value is .25 index points, or $12.50 per contract. This means that if the futures contract moves the minimum price increment (one tick), say, from 920.00 to 920.25, a long (buying) position would be credited $12.50; a short (selling) position would be debited $12.50. All futures positions (and all short option positions) require posting of a performance bond (or margin). Positions are marked-to-the-market daily. Additional deposits into the margin account may be required beyond the initial amount if your position moves against you. (For an explanation of the mechanics of, and requirements for, futures and options trading at the CME, contact your broker.)
Mini S&P 500 contracts are cash settled, just like the standard S&P 500; there is no delivery of the individual stocks. Even better, Mini S&P 500 daily settlements and quarterly expirations will use the exact same price as the S&P 500. The same daily settlement prices allow Mini contracts to benefit from the liquidity of the S&P 500 futures.
Like the S&P 500, which is settled using a Special Opening Quotation (SOQ), all Mini S&P 500 positions are settled in cash to the same Special Opening Quotation on the third Friday of the quarterly contract month. What is the Special Opening Quotation, or SOQ, as it is often called? The final settlement price is an SOQ of the S&P 500 Index based on the opening prices of the component stocks in the Index, or on the last sale price of a stock that does not open for trading on the regularly scheduled day of final settlement.
Trading the Mini S&P 500 -- An Example
Let's say you are an individual investor who is bullish on the stock market. You have been following daily activity in financial newspapers and on financial news stations. You want to become involved in the stock market; however, you have only around $10,000 to invest. You see every day in the newspaper that the market, as tracked by the S&P 500, is moving, and you want to be a part of it. You have traded stocks before, but you've decided that being a stock picker is too difficult and time consuming. You also realize that you would have to limit your investment to just one or two individual stocks. Or, you could buy a mutual fund; however, that only allows you to value your assets based on the closing price each day, thus losing the trading opportunity within the day.
You might instead consider going long Mini S&P 500 futures contracts to profit from your bullish outlook. Up to this point, S&P 500 futures have been out of your reach, with the minimum requirement to put up far exceeding your total planned investment. Here's your opportunity. New Mini S&P 500 contracts allow you to put your investment dollars to work by purchasing Mini S&P 500 futures. Now you can participate in the leading stock index futures market at a fraction of the cost.
Mini S&P 500 -- The E-Mini
Futures & Options Contract Highlights
Mini S&P 500 Futures Mini S&P 500 Options on Futures
Ticker Symbol ES Calls: ES
Puts: ES
Contract Size $50 x Index One Mini S&P 500 futures Contract
Tick Size .25 index points
($12.50 per contract) .25 index points
($12.50 per contract)
Trading Hours 24-hour trading, except
3:15 p.m. - 3:30 p.m. (Chicago Time) Monday - Thursday
3:15 p.m. Friday - 5:00 p.m. Sunday
Contract Months March, June, September, December All 12 Calendar months (The underlying instrument for the three monthly option expirations within a quarter is the quarter-end futures contract.)
Last Day of Trading Trading can occur up to 8:30 a.m. (Chicago Time) on the third Friday of the contract month March, June, September, December:
Same date as underlying futures contract
Other eight months:
The third friday of the contract month
Strike Intervals Not Applicable 5-point intervals for two nearest contracts, 10-point intervals for deferred months
Quarterly Futures & Options Settlement Procedures:
Cash settlement. All open positions at the close of the final trading day are settled in cash to the Special Opening Quotation on Friday morning of the S&P 500 Index.
Contract specifications subject to change without notice. Check with your broker to confirm this information.
This information has been compiled for general information purposes only. Although every attempt has been made to ensure the accuracy of the information, Commodity Futures Trading Corp. assumes no responsibilities for any errors or omissions. All matters pertaining to rules and specifications herein are made subject to and are superseded by official Chicago Mercantile Exchange rules. Current CME Rules should be consulted in all cases concerning contract specifications.
. 
