The Pirates will receive four minor leaguers including right-handed pitcher Ross Ohlendorf, right-handed pitcher George Kontos, left-handed pitcher Phil Coke and right fielder Jose Tabata in return. The trade is tentative pending physicals.
"It's definitely a positive day for us," Johnny Damon said.
The Yankees, with Hideki Matsui and Jorge Posada on the disabled list and possibly lost for the year, needed another right-handed bat for their lefty loaded lineup.
Their all-righty bullpen has a 1.67 ERA over its last 23 games, and adding Marte gives them one of the top lefty specialists in baseball.
"There's so many unexpected things [that] happen this time of year," Alex Rodriguez said, "but when you hear those names, I don't think anyone can expect to get two quality players like that in the middle of their prime to help our team."
The Pirates pulled Nady after the first inning Friday night against San Diego.
Nady was in right field during the top of the first but was replaced by Jason Michaels in the field in the second. 
Nady
Marte
Marte, one of the most coveted left-handed specialists in the game, was caught by television cameras hugging teammates in the dugout after leaving the bullpen shortly after."There is a trade in place, pending medical reviews of all the players involved on both clubs," Pirates director of media relations Jim Trdinich said. "That is all that is permissible to be announced at this time."
The Tampa Bay Rays, New York Yankees and New York Mets all were thought to be interested in Nady, who was batting .330 with 13 home runs and 57 RBIs. Marte is 4-0 with a 3.47 ERA and 47 strikeouts in 46 2/3 innings, and also was attracting interest from several teams.
"They were two special guys in our clubhouse and two special guys on the field, and obviously they will be dearly missed," Pirates manager John Russell said.
Pittsburgh, 48-55 and in fifth place in the NL Central after a 6-5 loss to San Diego, is trying to rebuild and avoid a 16th consecutive losing season at the same time.
"We felt that this was the best move for the Pittsburgh Pirates as well as being a very good move for X and Damaso," Russell said.
Ohlendorf was 1-1 with a 6.53 ERA in 25 games with the Yankees this season. He was demoted on June 27, and had a 1-1 record with a 4.03 ERA in five starts with Triple-A Scranton/Wilkes-Barre.
Tabata, Kontos and Coke all were with Double-A Trenton. Tabata was batting .248 with three homers and 36 RBIs entering play Friday, and Coke was 9-4 with a 2.60 ERA in 20 games, 19 starts. Kontos was 3-9 with a 3.77 ERA in 20 starts.
High-ranking Yankees officials gathered for meetings at their spring training complex Thursday. After a three-hour meeting, co-chairman Hank Steinbrenner confirmed one of the topics was indicted home run king Barry Bonds.
Steinbrenner wouldn't say if the Yankees are interested in Bonds, but it appears highly unlikely the team will pursue him after acquiring Nady.
"It helps out the team, not only now but also in the long run," Damon said of acquiring Nady. "He's one of the most underrated players around. I think he's one of the best outfielders in the game."
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