The Nets have agreed to trade guard James Harden, a former Most Valuable Player Award winner, to the Philadelphia 76ers for a package centered on Ben Simmons, the former All-Star point guard who has not played this season for personal reasons, according to two people with knowledge of the deal who were not authorized to speak publicly.

ESPN was the first to report the news. The deal was expected to be completed Thursday evening.

The stunning trade brings about a sudden and unexpected end to the superstar grouping of Kyrie Irving, Kevin Durant and Harden, who were, on paper, leading one of the most talented teams ever. But the three stars had rarely played together since Harden was acquired from Houston last season, in part because of injuries and in part because of Irving’s refusal to be vaccinated against Covid-19, which has made him ineligible to play in home games in Brooklyn.

The Nets will also receive Seth Curry, a sharpshooting guard; Andre Drummond, a backup center and one of the best rebounders in N.B.A. history; and two first-round picks. The Nets are also trading Paul Millsap, a four-time All-Star who hasn’t played much this season.

Simmons has yet to take the floor this season. Sixers Coach Doc Rivers and the All-Star center Joel Embiid criticized Simmons after a poor showing in last season’s playoffs. In November, Simmons’s agent, Rich Paul, told The Athletic that the tension had taken a toll on Simmons’s mental health, and that he wasn’t ready to play basketball.

If he is able to play now, the Nets could use him. They have been in a free fall, losing nine in a row entering Thursday night’s game against the Washington Wizards — dropping them to eighth place in the Eastern Conference. Durant hasn’t played since Jan. 15 because of a knee injury, while Harden has been out with a hamstring injury since Feb. 2, when he turned in a listless 4-point performance against the Sacramento Kings. Irving has only appeared in 12 of the Nets’ 54 games.

The trade will reunite Harden with Daryl Morey, the president of basketball operations for Philadelphia. They last worked together in Houston, where Morey was the general manager.