In the summer of 1981, a four-way bidding war errupted over the control of Conoco Inc., the world's ninth-largest oil company. In the spring, Conoco stockholders had responded favorably to an offer from Dome Petroleum Limited for its Canadian subsidiary, leading large investors to conclude that the company was ripe for a hostile takeover.

Edward Jefferson (1921-2006), the new CEO of the DuPont Company, wanted to acquire Conoco as a source of feedstocks to protect the company from oil shocks of the sort that had occurred during the 1970s. The Bronfmans of the Seagram Company, Ltd., the multinational distiller, also bid for Conoco and learned that DuPont was the leading suitor. Conoco received another tender from the Mobil Corporation.

Conoco management favored DuPont and was suspicious of Seagram, fearing it would simply resell or dismantle the company. In the meantime, all of the contenders continued to buy Conoco shares in an attempt to influence the selection. DuPont and Conoco closed the deal on September 30, 1981. Conoco became a DuPont subsidiary at a cost of $7.8 billion in the largest U.S. business deal up to that time. Control of Conoco also included its subsidiary, Consolidation Coal Company, one of the two largest U.S. producers of bituminous coal, and DuPont switched several of its plants from oil to coal.

The exchange of shares, however, resulted in Seagram obtaining 24.5 percent of DuPont's common stock and three seats on DuPont's board of directors.

Furthermore, oil prices fell during the 1980s in response to greater conservation and efficiency, and DuPont moved away from oil-dependent products. In 1998, oil prices dropped sharply causing DuPont's stock value to fall from 84 to 53 dollars per share. DuPont sold 30 percent of Conoco in a public offering in October 1998 and sold the remaining 70 percent back to Conoco in 1998 and 1999.