  We consider spherically symmetric linear perturbations of static spherically
symmetric spacetimes where the matter content is ellectrically counterpoised
dust. We show that the evolution equation for the fluid perturbation implies
that the fluid elements move with constant velocities. Therefore there are
neither oscillations nor exponential departure from the background solution. We
present an explicit example that shows that the perturbation could lead to the
formation of a black hole.
