Screening of the Reissner-Nordstr\"om charge by a thin-shell of dust matter

A concentric charged thin-shell encircling a Reissner-Nordstr"{o}m black hole screens the clectric / magnetic charge completely to match with an external Schwarzschild black hole. The negative mass thin-shell is shown to be stable against radial perturbations. It is shown further that by reversing the roles of inside Reissner-Nordstr"{o}m and outside Schwarzschild geometries the mass of the appropriate shell becomes positive.