CFD Quotes

Similar to Forex, CFDs are quoted with a bid and an ask price. So the CFD for the S&P500 might be quoted as follows:

S&P 500 826.75 / 827.25

The first number in the series represents the bid price, the cost of selling the S&P 500 CFD, or going ‘short' on the underlying index. If a trader believes the S&P 500 index will decline, a trader should sell the CFD.
 
The second number represents the ask price, the cost of buying the S&P 500 CFD, or going ‘long’ on the underlying index. If a trader believes the S&P 500 index will rise, a trader should buy the CFD.
 
The difference between the ask price and the bid price is called the spread.
 
What is a tick?

A tick is the smallest price increment in a futures or CFD price.  Often referred to as a "pip" in the currency markets.  Using the example above, if the CFD quote for the S&P 500 moved from 826.25 to 826.26, it will have moved one tick.

Since index and commodity CFDs traded with ICM are quoted in USD, a one tick move in the S&P 500 CFD is equivalent to a move of one cent.