The younger brother of Leeds United winger Brenden Aaronson is set to sign for Eintracht Frankfurt.
Paxton Aaronsen is moving to the Bundesliga this season.
ESPN says Frankfurt and Philadelphia Union have reached an agreement on a price for the 19-year-old attacker.
Paxton only needs to pass a medical with the Germans and negotiate personal terms.
Frankfurt must pay in the region of $4m for Paxten Aaronson to close the deal.