The Hawks, Celtics and Brooklyn Nets agreed on Tuesday to a three-team deal in which the Hawks will receive Porziņģis and a future second-round draft pick, the Nets will receive Terance Mann and Atlanta's 22nd pick in this year's draft, while the Celtics will get Georges Niang and a future second-round draft pick.
Although the teams have agreed on the trade, it is expected to be approved after 6 July.
The Hawks finished eighth in the Eastern Conference in the regular season but lost both play-in games and failed to qualify for the playoffs.
In 2024, Porziņģis became the first Latvian basketball player in history to win an NBA championship with the Celtics.
Porziņģis, who will turn 30 this summer, joined Boston last year in a trade from the Washington Wizards.
He has also played for the New York Knicks, who selected him fourth overall in the 2015 draft, and the Dallas Mavericks.
Porziņģis has one season remaining on his current contract, worth just under $31 million.
This season, the Latvian averaged 19.5 points, 6.8 rebounds, 2.1 assists and 1.5 blocks in 29 minutes per game in 42 regular season games.
In the playoffs, he averaged 7.7 points and 4.6 rebounds in 21 minutes per game, playing limited minutes due to illness. Porziņģis has ten seasons in the NBA behind him, one of which he missed entirely due to injury.
He has played in 501 regular-season games, averaging 19.6 points, 7.8 rebounds, 1.8 assists and 1.8 blocks in 31 minutes per game. In 28 playoff games, he averaged 11.9 points and 5.2 rebounds in 26 minutes.
Before his NBA debut in 2015, Porziņģis played for the Spanish club Sevilla.
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