Iso-butane stock levels were down 13% over a six-month period running from May 2009 to October 2009 when stocks fell from 572,000 barrels (bbls) to 496,000 bbls according to the most recent data available from the U.S. Energy Information Administration (EIA).

The drop was even greater from September to October, as stocks fell 27% from 679,000 bbls. Although the stock level was up 9% over a 12-month period, both the October 2008 and October 2009 stock levels were on the lower-end of historical norms for the month.

The EIA defines iso-butanes as “a normally gaseous branch-chain hydrocarbon. It is a colorless paraffinic gas that boils at a temperature of 10.9ºF. It is extracted from natural gas or refinery gas streams.” – Frank Nieto