So he's leading a price war against you. Which may not be a very good idea from him, depending on your relative strengths.
I have 50% market share against one specific opponent despite heavy prices(standard + 30%), and roughly the same market share against another specific opponent, but with muuuuuch lower prices(Standard- - 20%). Which means that the first opponent earns a lot of money(and me too on those lines), and the second one struggles to survive.(that's in GW3, but game mechanics are the same everywhere)