The Pirates parted with right-hander Ross Ohlendorf and MLB.com reported that the three prospects are believed to be southpaw Phil Coke, outfielder Jose Tabata and right-hander George Kontos.
New York -- who started Friday night's game against the Boston Red Sox three games behind Tampa Bay in the American League East -- strengthened itself for the regular-season stretch run by acquiring two players having career seasons.
Nady was batting .330 with 13 home runs and 57 RBI in 90 games (327 at-bats). He started Pittsburgh's contest against San Diego Friday night, but was pulled after one inning.
Marte, considered one of major league baseball's best middle relievers, is 4-0 with 16 walks and 47 strikeouts and a 3.47 ERA in 46 2/3 innings. He was spotted hugging ex-teammates before leaving Pittsburgh's bullpen.