Your original sentence says 他们在美国垄断了汇源, which I guess they intend to say "They monopolized the funding sources in America". A previous answer suggested a company name Hui Yuan ( Chinese fruit juice manufacturer that was the subject of an M&A by Coca Cola), but in my opinion that doesn't make sense; because the sentence would then read "They monopolized Hui Yuan in America."
Perhaps you could provide more contextual information.