  We predict an anomalous bias dependence of the spin transfer torque parallel
to interface, $T_{||}$, in magnetic tunnel junctions (MTJ), which can be
selectively tuned by the exchange splitting. It may exhibit a sign reversal
{\it without} a corresponding sign reversal of the bias or even a quadratic
bias dependence. We demonstrate that the underlying mechanism is the interplay
of spin currents for the ferromagnetic (antiferromagnetic) configurations,
which vary linearly (quadratically) with bias, respectively, due to the
symmetric (asymmetric) nature of the barrier. The spin transfer torque
perpendicular to interface exhibits a quadratic bias dependence.
