I'm just going with an Atlantic-Pacific corporation that would be the go-to guys for smuggling, shipping, illegal weapons, and with richer nations/countries, more advanced, efficient body armors, weapons, etc.

Antimatter is only going to be a side thing. If suddenly people put a crapload towards them, progress will ensue. Otherwise, a small fund is issued to them each year to keep it in working condition.

An ocean-based shipping and weapons dealer, both illegal and cheap, or expensive and advanced.