Per The Vertical's sources, Nike was required to shell out more money for Simmons than the brand usually would for a rookie. Charania writes that the possible Simmons deal is believed to be one of the Swoosh's largest rookie deals ever.
Reports previously surfaced of Simmons potentially signing with adidas, which is looking less and less likely.
Simmons, who played his only year of college ball last season with the LSU Tigers, is expected to be one of, if not the, top pick in the 2016 NBA draft.
Simmons is signed to the LeBron James-funded Klutch Sports Group, an agency whose roster is composed almost entirely of Nike athletes.
UPDATE 6/7: Simmons has confirmed his signing with Nike in the above video.