Grant averaged career highs of 9.7 points and 4.7 rebounds for the Sixers last season and played in two games this season before the trade.
"This is a unique deal that allows us to address both short-term needs and longer-term goals at the same time," Sixers president of basketball operations Bryan Colangelo said in a statement. "Ersan will bring us much needed perimeter shooting, floor spacing and roster balance, while the acquisition of a future pick or picks should continue to drive our ability to generate future roster building options."
The Thunder will send a first-round pick in 2020 unless that selection falls within the top 20. In that case, Oklahoma City would send second-round picks in 2022 and 2023.