Transverse runaway velocities for systems which remain bound after the SN of the primary, for conservative (upper panel) and non-conservative (lower panel) mass transfer. Large grey points show the location of observed HMXB velocities from Chevalier & Ilovaisky (1998) for systems with Be companions (circles) and supergiant companions (triangles). Periods are obtained from the catalogue of Liu, van Paradijs & van den Heuvel (2000) and references therein.