Subsidiaries of Noble Energy, Inc. and Marathon Oil Company each own 45% of Atlantic Methanol Production Company LLC. The remaining 10% is held by SONAGAS GE (Sociedad Nacional de Gas de G.E.).

In the U.S., subsidiaries of Samedan and Marathon each also hold 50% ownership in the U.S. companies, AMPCO Marketing, L.L.C. and AMPCO Services, L.L.C.

The Marathon holdings were purchased from the original joint venture partner, CMS Energy, on January 3, 2002.