  We study the effects of a magnetic field on the chaotic dynamics of a string
with endpoints on the boundary of an asymptotically AdS$_5$ space with black
hole. We study Poincar\'e sections and compute the Lyapunov exponents for the
string perturbed from the static configuration, for two different orientations,
with position of the endpoints on the boundary orthogonal and parallel to the
magnetic field. We find that the magnetic field stabilizes the string dynamics,
with the largest Lyapunov exponent remaining below the
Maldacena-Shenker-Stanford bound.
