A Note on the Collision of Reissner-Nordstr\"om Gravitational Shock   Waves in AdS
  We study the collision of two Reissner-Nordstr\"om gravitational shock waves in AdS and show that the charge completely prevents the formation of marginally trapped surfaces of the Penrose type with topology S^(D-2), independently of the energy and the value of the impact parameter. In the case of head-on collisions, a numerical analysis shows that no trapped surfaces with topology S^1 \times S^(D-3) form either. 
Alvaro Duenas-Vidal, Miguel A. Vazquez-Mozo
hep-th gr-qc