Velocity shear instabilition associated with plasma motion across a magnetic fie .a{background-color: #ffff88}.h{background-color: #ffff00}.b{background-color: #ccccff}.i{background-color: #3333ff}.c{background-color: #ffcccc}.j{background-color: #ff3333}.d{background-color: #bbffff}.k{background-color: #00ffff}.e{background-color: #ffdd77}.l{background-color: #ff6600}.f{background-color: #ccffaa}.m{background-color: #33ff00}.g{background-color: #ffccff}.n{background-color: #ff00ff} a:link {color: #0000ff} a.oa:link {color: #00a000} a:visited {color: #4000a0} a.oa:visited {color: #006666} a:hover {color: #ff0000} a.oa:hover {color: #cc33cc} The stability of stationary Vlasov equilibria simulating the motion of plasma across a transverse magnetic field has been analyzed. The stability analysis is based on the Vlasov-Poisson equations together with an assumption of finite larmor radius ordering. Especially the instabilities associated with velocity shear transitions separating plasmas moving in opposite directions have been considered. Two extreme cases of such velocity shear transitions are studied, one where the confining current is only due to ions and one where the containing current is only due to electrons.