We prove that when the number of (potential) buyers is at least three, every ex post equilibrium in the Vickrey-Clarke-Groves combinatorial auction mechanisms is a bundling equilibrium and is symmetric. This complements a theorem proved by Holzman, Kfir-Dahav, Monderer, and Tennenholtz (2003), according to which, the symmetric bundling equilibria are precisely those defined by a quasi-field. (C) 2003 Elsevier Inc. All rights reserved.