  We theoretically study the Hall response of a lattice system following a
quench where the topology of a filled band is suddenly changed. In the limit
where the physics is dominated by a single Dirac cone, we find that the change
in the Hall conductivity is two-thirds of the quantum of conductivity. We
explore this universal behavior in the Haldane model, and discuss cold-atom
experiments for its observation. Beyond linear response, the Hall effect
crosses over from fractional to integer values. We investigate finite-size
effects, and the role of the harmonic confinement.
