Chevron Corp. has prevailed in a 20-month fight to buy Hess Corp. for $53 billion, overcoming a challenge by arch rival Exxon Mobil Corp. that was unprecedented in the modern history of Big Oil.

The conclusion of the saga removes a stock overhang for Chevron and paves the way for the $53 billion deal to close immediately, which the oil giant said it could happen within a couple of days.

Chevron has a clear way for the major oil company to complete its $53 billion acquisition of Hess Corporation’s offshore assets in Guyana.