The Nets are understood to have acquired three-time scoring champion Harden in a deal that reunites him with Kevin Durant and gives him the move that he has sought for weeks.

The Nets will now have a Big 3 of Durant, Harden and Kyrie Irving.

The Philadelphia 76ers were reportedly considering a move for Harden that would have involved trading away Simmons but instead the three-times NBA scoring champion is headed to the Nets.

The four-team deal also involves the Indiana Pacers and Cleveland Cavaliers, although the NBA is yet to officially sign off on the trade deal which includes at least four draft picks and additional pick swaps.

Aussie Dante Exum will leave the Cavs for the Rockets as he continues his recovery from a calf injury, Victor Oladipo will go from Indiana to Houston, Caris Levert is moved from Brooklyn to Indiana while Jarrett Allen and Taurean Prince are headed to Cleveland from the Nets.

The trade for Harden was struck less than 24 hours after he seemed to deliver a farewell address of sorts after the Rockets' loss to the Los Angeles Lakers on Tuesday night.

"We're just not good enough ... I love this city. I literally have done everything that I can," the 31-year-old Harden said.

"I mean, this situation is crazy. It's something that I don't think can be fixed."

It couldn't, and now he's gone.

It was obvious the end was nearing Wednesday, when the Rockets told him they didn't want him at practice after his inflammatory comments about the team.

"We felt it was best for James and best for the group for him not to come to practice," first-year coach Stephen Silas said.

The Rockets are 3-6 so far this season and only the Minnesota Timberwolves have a worse record in the Western Conference.

New arrival John Wall, who was recruited in a trade for Russell Westbrook in the off-season, called the situation "rocky".

Veteran centre DeMarcus Cousins, who is in his first year in Houston after signing as a free agent, was far more direct.

"The disrespect (from Harden) started way before any interview," Cousins said.

"Just the approach to training camp showing up the way he did, the antics off the court.

"I mean, disrespect started way before. So this isn't something that all of a sudden happened last night."

Harden reported late for training camp and was fined $50,000 earlier this season for conduct detrimental to the league related to him not following the health and safety protocols put into place by the NBA and the National Basketball Players Association for navigating a season during the pandemic.

Australian Associated Press