Choose the spread and the number of years of past data to include and this program will generate the spread's seasonal. Then the nearest open spread is plotted along with the seasonal so that it can be put in historical context. The seasonal is made by a simple averaging process and has the same units as the spread.

The black line is the seasonal, the gray lines are the seasonal plus or minus one standard deviation and the blue line is the nearest open spread. The standard deviations have been smoothed to remove daily fluctuations.

1. Pick the commodities and the months. The contracts are aligned so that Commodity 1 expires before Commodity 2. For example, if Dec corn versus Mar corn are selected, the following alignment results:

   Dec Corn_1994 / Mar Corn_1995

   Dec Corn_1995 / Mar Corn_1996

   .

   .

   .

   Dec Corn_2003 / Mar Corn_2004

   If the months are switched, a different alignment results:

   Mar Corn_1995 / Dec Corn_1995

   Mar Corn_1996 / Dec Corn_1996

   .

   .

   .

   Mar Corn_2003 / Dec Corn_2003

2. Select the position. If Commodity 1 is long, then Commodity 2 is short, and vice-versa.

3. Select the numbers of contracts.

4. Enter the unit moves if these are different than the contracts you are trading (these inputs display only for intercommodity spreads.

5. Select the chart type. The jpegs are faster; the applets are interactive (zooming in is possible and there are data popups).

6. Select the amount of data to download. Using weekly closes rather than daily closes increases the download speed considerably.

7. Press "Get Chart". There's a lot of data to download, so be patient.

This is a limited set of commodities available to nonsubscribers. Subscribers can access data for over 40 commodities.