Arsenal and the Turkish club had already reached agreement on a fee worth around £17m, but the deal was still waiting on Trossard himself to settle personal terms.
That final piece appears close to falling into place, with The Athletic reporting the Belgian would earn in the region of £7.7m a year should he put pen to paper. The report stressed that some details still need to be finalised before the move can be completed.
Trossard, 31, has made 174 appearances for Arsenal since joining in 2023, scoring 36 goals and adding 34 assists, numbers that reflect the consistent, versatile contribution he has made across parts of four seasons at the Emirates.
His departure would bring an end to a spell that included a title-winning campaign and some memorable moments along the way, even as Arsenal now face the task of reshaping their options out wide.
Arsenal originally signed Trossard from Brighton in January 2023 after missing out on Mykhailo Mudryk, who chose Chelsea instead, and the Belgian quickly proved to be shrewd business, registering ten assists in his first 20 Premier League appearances.
His most iconic contribution came far more recently, though, with a dramatic 83rd-minute winner away at West Ham last season that helped Arsenal maintain their advantage over Manchester City during a tense run-in to the title.
Despite signing a new deal with a significant pay rise last August, his contract was never extended beyond next summer, leaving Arsenal with a narrow window to cash in before risking losing him for nothing.
With Trossard's exit, Gabriel Martinelli would become the club's only recognised specialist on the left, adding urgency to Arsenal's search for reinforcements out wide before the transfer window closes.