Napoli has signed Canadian-born Dutch midfielder Jonathan De Guzman and sent Argentina defender Federico Fernandez to Swansea.
De Guzman spent the past two seasons on loan at Swansea from Spanish club Villarreal, scoring nine goals in 59 league appearances.
"I am happy to have come to Napoli," he said. "I can't wait to start."
The 26-year-old De Guzman, who grew up in a suburb of Toronto, played in all seven of the Netherlands' matches at the World Cup in Brazil.
Both deals are permanent with neither club revealing the transfer fees.
Fernandez has been at Napoli since joining from Estudiantes in 2011. The 25-year-old defender made four appearances for Argentina in Brazil, but was an unused substitute in the loss to Germany in the final.