The S&P 500 e-mini contract. In the broadcast we use this as our primary instrument to define market direction and effect short term trades when we have a bias in the market. This is the electronic contract that trades around the clock, as opposed to the pit traded contract. Sometimes the pit traded version is called the “big contract”. Futures contracts on are denoted by two letters and then a letter and a number to define their expiration month. The ES has four contract periods per year which expire in March, June, September, and December. These four months are denoted by the letters H, M, U, and Z. For example, if it was 2012, then the March contract would be called the /ESH2. Thinkorswim requires a forward slash before the letters. Certain trading platforms and charting packages may denote this differently, either with or without the forward slash or putting a space somewhere between the letters and numbers such as ES H2.