Seattle Sounders FC has been active in the transfer market, bringing in impactful players and, in some cases, selling homegrown or acquired talent to clubs abroad. The MLS transfer market has evolved significantly, with transfer fees both paid and received increasing each year as the league grows in stature.
MLS clubs can acquire players through various mechanisms including transfer fees, free transfers, loans, and the league's unique allocation systems (GAM and TAM). Seattle Sounders has used all of these tools to build competitive rosters. Outgoing transfers to European clubs have also become an important part of the ecosystem, as selling young talent at a profit helps fund future acquisitions and validates the club's player development pathway.