The Philadelphia 76ers offered All-Star guard Ben Simmons a five-year, $170 million maximum extension, and the sides are working through contract details toward an eventual agreement, league sources tell ESPN.

Sixers general manager Elton Brand and Simmons' agent, Rich Paul of Klutch Sports, have until mid-October to finalize a rookie extension, but there's a shared expectation a signed agreement will come significantly sooner, league sources said.

Simmons, the 2016 No. 1 overall pick and 2018 NBA Rookie of the Year, is one of the cornerstone stars for the 76ers. His teammates, including All-Star center Joel Embiid (five years, $150 million), Tobias Harris (five years, $180 million) and Al Horford (four years, $109 million) have been secured with long-term deals.

Simmons, 22, averaged 16.9 points, 8.8 rebounds and 7.7 assists for the Sixers last season. At 6-foot-10, he has one of the NBA's most unique skill sets as a playmaker and finisher at the rim.