Rubin, whose fortune Forbes estimates at $3 billion, is the majority owner of Conshohocken-based Kynetic, the holding company for e-commerce retailers Fanatics, Rue La La, and ShopRunner. Kynetic was valued at $4.5 billion one year ago after raising $1 billion from Softbank. Rubin also owns a minority stake in the 76ers and the N.J. Devils.