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 will proceed with its $53 billion acquisition of Hess, after it prevailed in a landmark legal battle against larger rival Exxon Mobil to gain access to the largest oil discovery in decades.