  We show that smeared brane solutions, where a charged black p-brane is
smeared uniformly over one of the transverse directions, can have a
Gregory-Laflamme type dynamical instability in the smeared direction even when
the solution is locally thermodynamically stable. These thus provide
counterexamples to the Gubser-Mitra conjecture, which links local dynamical and
thermodynamic stability. The existence of a dynamical instability is
demonstrated by exploiting an ansatz due to Harmark and Obers, which relates
charged solutions to neutral ones.
