Voit, 27, appeared in eight games for St. Louis this season, hitting .182 with one home run and three RBIs, but he has spent the majority of the year in Triple-A Memphis, where he has slashed .299/.391/.500 with nine home runs and 36 RBIs in 67 games.
The Yankees have been linked to right-hander Osiel Rodriguez, who was ranked by MLB Pipeline as the ninth-best prospect in the current international class, and this trade could set the stage for a deal expected to be in the $1.1 million range. The Yankees, who have about $1.15 million to spend, could use most of the newly acquired pool money to sign Rodríguez or spread it out to add another prospect.
With both Aaron Judge and Gary Sanchez on the disabled list, it was expected that the Yankees would make a move to add a bat to the lineup, but Shreve was unsure if he would be involved.
"I knew we had to make a move, I just didn't know what it was going to be," Shreve said. "I mean, I've prepared myself for it."
Shreve, 28, went 2-2 with one save and a 4.26 ERA over 38 innings in relief this season, while Gallegos, 26, accumulated a 4.50 ERA in four Major League appearances this year and a 3.90 ERA with two saves in 27 2/3 innings in Triple-A Scranton/Wilkes-Barre.
"I'll have a good opportunity over there," Shreve said. "I love it here. I mean, these are my friends. I've been here four years, and it's going to suck to leave."
Because J.A. Happ served as the Yankees' "26th man" for Saturday's doubleheader, he will ultimately take Shreve's spot on the 25-man roster, thus leaving no room for the Yankees to add Tommy Kahnle, who has been in the Minors since June 4.
Voit will most likely be headed to Scranton/Wilkes-Barre.
Mandy Bell is a reporter for MLB.com based in New York.