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.

Chevron closed its $55 billion acquisition of Hess on Friday after winning a landmark legal battle against larger rival Exxon Mobil to gain access to the biggest oil discovery in decades - the Stabroek Block off the coast of Guyana,

The conclusion of the saga removes a stock overhang for Chevron and paved the way for the $53 billion deal to close immediately.