Rack, it was for their previous purchases of Kerr-McGee and Western Gas. (Edit: Sorry, I see AMJ already posted.)
"HOUSTON--(BUSINESS WIRE)--Sept. 8, 2006--Anadarko Petroleum Corporation (NYSE:APC) today announced it intends to commence a public offering of $5 billion of new issue senior notes. The offering is expected to include senior floating rate notes due 2009, senior fixed rate notes due 2016 and senior fixed rate notes due 2036. Anadarko intends to use the net proceeds from the offering to repay borrowings under its 364-day term loan agreement, which were used to finance its acquisitions of Kerr-McGee Corporation and Western Gas Resources, Inc."