Hephaestus Industries is the leading market share in small arms, planetary armed vehicles and defense/security systems. They are also known for war-profiteering, well-known for selling weapons to both sides of a dispute, or even their own competitors – as long as the weapons are not used on them and one has the thalers, they will sell you whatever you wish. These and other factors have helped them become the most profitable arms manufacturer in human space and one of the four great megacorporations of humanity.
Alien technology has a rather significant research branch in Hephaestus Industries, in particular ancient Unathi weaponry and whatever gets funneled to them by the Skrell. Meanwhile, their Phoron research branch is practically non-existent – rumor has it they are letting their competitors, in particular NanoTrasen, take the risks and costs of Phoron accidents and do the basic grunt work before stepping back in. This is purely rumor, and all incidents of corporate spies that claimed to be on HI's payroll have been denied by Hephaestus Industries.
Due to their nature, and the necessary evil of being a major arms industry, Hephaestus Industries are the under constant scrutiny and are generally disliked by more peaceful systems. They are also considered one of the best megacorporations to work for, with the highest pay rates, best benefits that last well past retirement. A job at Hephaestus Industries is one of the hardest, but most sought after, positions, and those who make it in and are loyal are often considered set for life.
During the later half of the 21st century, the leading weapon manufacturers of Germany, Rheinmetall, Thyssen-Krupp, Walther, and Heckler and Koch banded together into Hephaestus Industries to combat dwindling exports and profits. The combination of their knowledge and assets went to an advent of weapon technology in the heart of Europe and before long several other corporations that also focused in heavy industries and arms manufacturing were bought out and integrated. It was this perhaps that helped them weather the great economic collapse of Earth and allowed them to supply virtually every warring faction of Earth with arms and vehicles to form their own military. The vast amount of funds earned during the disputes earned Hephaestus Industries enough funds to become the first interplanetary corporation after the formation of Sol Central, and later led their expansion to become humanity's first true megacorporation.
When Phoron was discovered in the second half of the 23rd century, Hephaestus Industries looked into the potential of the new found element but backed down when NanoTrasen formed and fought tooth and nail for all known deposits. Among the megacorporations, Hephaestus Industries shares the most amiable relations with humanity's allies, in particular the Unathi.