  Magnetars are fascinating objects that are thought to be neutron stars
powered by their strong internal magnetic fields. Clear evidence of a sudden
spin-down was detected in the Anomalous X-ray Pulsar AXP 1E 2259+586, an object
cataloged as a magnetar. This event received the name "anti-glitch". In this
work we present a simple internal mechanism which could account for the
observed sudden spin-down of the star.
