Online fast fashion juggernaut Shein and SPARC Group — a joint venture between licensing firm Authentic Brands Group and mall operator Simon Property Group — have formed a partnership that could see Forever 21 clothing and accessories sold on Shein’s site, and Shein roll out shop-in-shops inside Forever 21 Stores.As part of the deal, Shein acquired a one-third interest in SPARC, and SPARC became a minority shareholder in Shein. Shein’s vast e-commerce platform will expand distribution for ailing mall brand Forever 21, and allow Shein to test brick-and-mortar. (The retailer hosted pop-ups in London and Las Vegas this year, and opened a showroom in Tokyo in 2022.) SPARC Group’s other brands include Aeropostale, Brooks Brothers and Lucky Brands.The collaboration marks the latest move by Shein to evolve away from its status as anonymous seller of trendy, ultra cheap clothing as it faces new competition from upstarts like Temu, continued scrutiny from US lawmakers. Shein has set its sights on recruiting third-party sellers to expand its offer outside products it manufactures, putting it more in league with e-commerce marketplaces including Amazon. Fashion brands Paul Smith and Stuart Weitzman are among those who have already signed on.Learn more:Shein’s Years of Explosive Growth Are Over. What’s Next?The fast-fashion retailer has seen sales decline in six of the last seven months, as the novelty of its endless selection of trendy, ultra-cheap clothes wears off.