Lockheed Martin (LMT) is the largest US defense contractor, with a wide portfolio of products offered. Currently, Lockheed’s Terminal High Altitude Area Defense (THAAD) missile is the only US anti-missile defense system that's capable of targeting incoming ICBM warheads upon re-entry. Currently, Lockheed has an ongoing $528M contract for THAAD systems, with has expanded to over $1B between the system costs and the support contract.
I believe that missile defense revenue will continue to grow, especially as the US and its allies move away from a boots on the ground to a tactical strike methodology employed by the Obama administration. Additionally, as nations such as Iran and North Korea work on strike capacity, anti-ICBM capability will see strong demand, particularly from US allies in the Middle East and Asia. For example, North Korea’s most recent missile testing has analysts believing that the newest iteration has a potential range of 13,000 km, up from the July test which demonstrated a potential range of 10,000 km. That would give the missile the range to cover most of the continental US, depending on warhead weight, not to mention most of Asia.