Answer
The trade occurred in 2013, when the Brooklyn Nets acquired Paul Pierce from the Boston Celtics in exchange for Gerald Wallace, Kris Humphries, MarShon Brooks, and a protected 2014 first-round draft pick. The move was part of a larger roster overhaul by the Celtics following their defeat in the 2012 NBA Finals, and it marked the end of Pierce's 15-year tenure with the team.