U.S. government-services contractor Leidos is in final negotiations with NATO over a deal to help build the alliance's ballistic missile defense shield, according to industry sources. The Reston, VA-based company won the race for a systems engineering and integration contract initially valued at roughly $90 million by underbidding the competition, these sources said. The deal would enable Leidos to maintain a solid foothold for the next half-decade or so in NATO ballistic missile defense as the go-to firm for the...