Newcastle have signed Argentina defender Federico Fernandez from Championship side Swansea for a reported £6m fee on a two-year deal.
The 29-year-old played under Magpies boss Rafael Benitez at Napoli, where he won two Coppa Italia titles, before joining Swansea in 2014.
Fernandez played 128 games at the Liberty Stadium, scoring twice.
“It was a long day but I’m really happy to be here,” said Fernandez. “It is a new challenge in my life.”
Benitez added: “I know Federico well from our time together at Napoli and it was an easy decision to bring him here.
“He is experienced, a very good professional and he will add competition in defence.”
Fernandez becomes Newcastle’s seventh signing of the summer transfer window, joining goalkeeper Martin Dubravka, defender Fabian Schar, midfielders Ki Sung-yeung and Kenedy, and strikers Salomon Rondon and Yoshinori Muto.