Simmons has refused to play for the Sixers this season after coach Doc Rivers and center Joel Embiid were critical of his performances in the Eastern Conference semifinals loss to the Atlanta Hawks last season.
Philadelphia had been trying to trade the fifth-year guard/forward ever since, but the former Rookie of the Year's value plummeted after he came up short against the Hawks.
However, according to multiple reports a deal was finally struck to send Simmons to Brooklyn in exchange for the 2018 NBA MVP Harden. Seth Curry, Andre Drummond, an unprotected 2022 first-round pick and a protected 2027 first-round pick were also sent to the Nets, with Paul Millsap going in the opposite direction.
Harden can become a free agent in the offseason, while Simmons is under contract until 2025 after signing a five-year, $177.2million deal in 2019.
While the 76ers seemingly boosted their chances of contending by adding Harden, the Los Angeles Lakers and Golden State Warriors remained idle. However, there were still plenty of other deals reported on Thursday.
Mavericks move on from Porzingis
The Luka Doncic-Kristaps Porzingis era is over in Dallas.
The Mavs sent Porzingis and a second-round pick to the Washington Wizards in exchange for Spencer Dinwiddie and Davis Bertans.
Injuries have continued to trouble the 7ft 3in center, who averaged 20 points and 8.8 rebounds per game in two and a half seasons in Dallas.
Kings trade Bagley, Bucks get Ibaka
The Sacramento Kings made Marvin Bagley III the second overall pick in the 2018 draft but brought an end to his time in California as part of a seven-player, four-team trade.
Bagley was sent to the Detroit Pistons, with Josh Jackson and Trey Lyles going to Sacramento. The Kings also received Donte DiVincenzo from the Milwaukee Bucks, who swapped Serge Ibaka for Semi Ojeleye and Rodney Hood. The reigning NBA champions also received two future second-round picks and cash considerations.
Bagley has started just 17 games for Sacramento this season, averaging 9.3 points and 7.2 rebounds in 21.9 minutes per game.
Celtics bring Theis back, send Schroder to Houston
Daniel Theis is back for a second spell with the Boston Celtics.
Less than a year after he was traded to the Chicago Bulls by the Celtics, Theis was brought back from the Houston Rockets in exchange for Dennis Schroder, Enes Freedom and Bruno Fernando. Freedom is expected to be waived by the Rockets, though.
Boston also sent Bol Bol and PJ Dozier, who are both out for the season, to the Orlando Magic and offloaded Josh Richardson and Romeo Langford to the San Antonio Spurs. The Celtics' brought in Derrick White.
Elsewhere...
Goran Dragic's time with the Toronto Raptors is up after he was traded to the Spurs for Thaddeus Young, Drew Eubanks – whom they were set to waive – and a 2022 lottery-protected first-round pick. Dragic is expected to be bought out, with the Chicago Bulls, Mavs, Bucks, Warriors, Nets and Clippers all credited with an interest.
The Charlotte Hornets added Montrezl Harrel from the Wizards. Ish Smith and Vernon Carey Jr went the other way.
Torrey Craig is back with the Phoenix Suns following a deal that saw Jalen Smith land with the Indiana Pacers. Aaron Holiday was also acquired from the Wizards.