The actual inventories of crude oil, gasoline, and distillate, such as jet fuel, as reported on a weekly basis. The numbers are watched closely by the energy markets, and if the results differ greatly from the expected inventory levels, the market can react strongly. The inventory data can be skewed by holidays and seasonal factors. Weekly data can be unreliable and should be viewed as a part of longer-term trends, so a four-week moving average may be more useful.
There are two sets of inventory data that comprise the crude oil inventory reports. The American Petroleum Institute, a private trade group, compiles a voluntary survey of its members and releases the data weekly. The Energy Information Agency, a U.S. government agency, compiles mandatory reports from firms in the energy industry and releases the data on Wednesday mornings.