Only if the market is inherently local or the combination with result in increased prices. Market sizes vary. For airlines they look at cities or even specific

Only if the market is inherently local or the combination with result in increased prices. Market sizes vary. For airlines they look at cities or even specific airports. it doesn't matter that there are a million different airlines, if your merger creates a quasi monopoly for flights into and out of some cities. That's why in airline deals, you often see one of the two sell off routes to third party competitors. But for chemicals and agriculture supplies--it's really an international marketplace. It doesn't really matter if they are the only US company as long as Chinese, Korean and German companies are active in selling in America. Though the DOJ will undoubtedly look at the deal hard. Make sure things like distribution chains, retail deals etc. don't create a monopolistic effect.