NEXT (not to be mistaken for the real-world NeXT) is a private group dealing in high technology, particularly computers. They are somewhat of a "friendly competitor" to ARC in a number of areas, but their competition does not stop them from working together when it's convenient. Dealing in bleeding-edge technology, they have their own highly trained intelligence and security staff. It's a mutant-friendly corporation, and the CEO, Willard Jennings, is a known philanthropist.
Merry was recruited to work for them, in the "black ops" section of the company. That seems to mean they do things that may not be bad - they may even be very good - but are not things that should be public knowledge. So far, that has meant working with the CIA to find and stop the supervillain the Palm, at least until various events made that a bad idea.