WASHINGTON (Reuters) - Lockheed Martin Corp , the Pentagon's largest supplier, has won a contract worth up to $1.91 billion to manage the U.S. military's Global Information Grid networks on a day-to-day basis, the U.S. Defense Department said on Friday.

It said the contract would run for three years and included two two-year options, which if picked up would make the total price $1.91 billion.

The contract includes a mix of firm-fixed-price, fixed-price with incentive, cost-plus-incentive-fee, and cost-plus and fixed-fee pricing plans, according to the Pentagon's announcement in its daily digest of big weapons deals.

(Reporting By Andrea Shalal-Esa; Editing by Gary Hill)