ULA, a joint venture between Lockheed Martin and Boeing, had the market cornered for launching satellites in the USA - until SpaceX hit. They're able to launch the military's newest GPS systems for millions of dollars less than ULA, and the Air Force is loving SpaceX's Falcon 9 system.
ULA's planning to replace their Atlas V launch vehicles with their new Vulcan LV, but those won't be operational for another two years - and even then, they won't be able to match or undercut the SpaceX LVs. On top of it, the SpaceX Falcon 9 series of launch vehicles are reusable; they can deliver a payload to orbit and then return to Earth, landing vertically on the launch-pad where they can be relatively quickly refurbished and refueled in preparation for subsequent launches. They plan to re-use one of their Falcons later this month, and that's a huge game-changer, assuming that the effort is successful. It's looking as though ULA's days are numbered unless Lockheed Martin and Boeing can come up with substantial cost reductions.