Olivier Theyskens, who spent nearly four years as the artistic director of Theory, is leaving the New York-based contemporary sportswear brand to "pursue other design projects," according to WWD.
The designer — who has dressed the likes of Reese Witherspoon, Emma Watson and, most recently, Greta Gerwig and Felicity Jones at this year's Met Gala — will present Theory's pre-spring 2015 line as his last collection for the fashion house.
"It has been an amazing opportunity to work with Andrew [Rosen, CEO of Theory] and to benefit from his knowledge in this dynamic segment of fashion," Theyskens told the publication. "I will always cherish our friendship."
While visiting L.A. last year for a lecture hosted by the Costume Council of LACMA, Theyskens said of the label, "We do not really change the collections for the markets. We want Theory to be a global brand. But we do think about cities where it is warmer."
Though the Belgium-born designer helped Theory gain global recognition, sources tell WWD that Theysken's designs "failed to ignite sales on the store floor."