Standard Oil of California and Gulf Oil merged in 1984, which was the largest merger in history at that time. To comply with U.S. antitrust law, California Standard divested many of Gulf's operating subsidiaries, and sold some Gulf stations and a refinery in the eastern United States. (The refinery is currently owned by Sunoco.) Among the assets sold off were Gulf's retail outlets in Gulf's home market of Pittsburgh, where Chevron lacks a retail presence but does retain a regional headquarters there as of 2013, partially for Marcellus Shale-related drilling. The same year, Standard Oil of California also took the opportunity to change its legal name to Chevron Corporation, since it had already been using the well-known "Chevron" retail brand name for decades. Chevron would sell the Gulf Oil trademarks for the entire U.S. to Cumberland Farms, the parent company of Gulf Oil LP, in 2010 after Cumberland Farms had a license to the Gulf trademark in the Northeastern United States since 1986.