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 paved the way for the $53 billion deal to close immediately.

Chevron completed its $53 billion purchase of Hess after winning an arbitration case brought by rival Exxon Mobil and the China National Offshore Oil Corporation.