Sampdoria skipper Angelo Palombo
Colombian forward Freddy Guarin, Italy midfielder Angelo Palombo and Brazilian defender Juan have all joined.
Guarin, 25, joins from Portuguese champions Porto on a four-and-a-half year deal following spells at Boca Juniors and French side St Etienne.
The Colombia international, who started his career with Envigado in his homeland, won two Portuguese titles with Porto and last season's Europa League.
Palombo, who was part of the Italy squad at the 2010 World Cup, spent the last six months in Serie B after refusing to leave relegated Sampdoria.
But the 30-year-old has now joined the nerazzurri on loan until the end of the season with an option to a permanent three-year deal at that juncture.
The 20-year-old Juan, not to be confused with his compatriot and namesake at Roma, has signed from Internacional until June 2016.
He can play at either centre-back or left-back.
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