On June 16, 1975 the Milwaukee Bucks traded Walt Wesley to the Los Angeles Lakers. Oh, and they included Kareem Abdul-Jabbar as well.
Kareem being traded is often cited as one of the worst trades ever, but it can only be seen as such without any context of the situation. The truth is there was no choice for the Bucks that would’ve turned out better than the trade Milwaukee made with Los Angeles.
This fantastic LA Times piece by Thomas Bonk has great details about the trade, including the now well-known fact that Kareem was the one who decided he would be leaving Milwaukee, because of Milwaukee.