The Philadelphia Union agreed to transfer homegrown midfielder Paxten Aaronson to Eintracht Frankfurt of the Bundesliga on Thursday for a multimillion-dollar transfer fee.
The Union will also retain a percentage of any future transfer fees for Aaronson, who will join Frankfurt in January.
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"Paxten has accomplished so much in a short amount of time. He has worked incredibly hard, and he has taken advantage of every opportunity with the first team, Union II and the U-20 National Team," Union sporting director Ernst Tanner said in a news release.
"There has been interest in him for a long time, and we feel this is the right move for the club and the player, putting him in a good situation to continue developing in one the best leagues in the world."
Aaronson, 19, tallied four goals in 37 matches (seven starts) in two seasons with the Union and came on as a substitute during Philadelphia's MLS Cup loss to LAFC on Nov. 5. He made his MLS debut in May of 2021.
"In Paxten Aaronson we were able to sign a sought-after and talented player who will give our attack even more flexibility in the future," Frankfurt sporting director Markus Krosche said. "We have a clear plan for him and want to build him up carefully. Paxten will get the necessary time from us to get used to his new environment and develop in the best possible way
The New Jersey native came through the same Union academy system that produced his brother Brenden, who left Philadelphia for FC Salzburg in January 2021 before joining Premier League side Leeds United this summer.
Union head coach Jim Curtin has previously said that the younger Aaronson was "going to be really special," noting that "obviously there's good genetics in the family."
Eintracht Frankfurt beat Barcelona, West Ham and Rangers en route to winning the Europa League last season. They have backed that up this campaign by qualifying for the Champions League knockout stages and currently sit fourth in the Bundesliga table while the league takes a hiatus during the World Cup.
ESPN's Tom Hamilton contributed to this story and information from Reuters was also used.