The NBA may be closer to a shorter season, a new postseason format and the in-season tournament Commissioner Adam Silver has long wanted as well.

A person familiar with the negotiations said Saturday the NBA is working with the players' union and its teams on a plan to shorten the regular season, possibly to 78 games. They also are considering a change to the playoff seeding and the addition of a midyear tournament for all 30 clubs in time for the 2021-22 season.

The tournament would likely be a way for teams to mitigate the loss of revenue from the shorter regular season and fewer home dates....