Color evolution of optical transient following GRB 140506A. Data are corrected for Galactic extinction, host-galaxy-subtracted, and given in AB magnitudes. The first two epochs evolve achromatically within errors, but then a clear color change is seen after three weeks, with the transient becoming both bluer in g′−r′ and redder in r′−z′. There is likely further evolution in the last epoch at 68 d, but the transient is no longer detected in g′ to a non-constraining limit, and the errors are large in the two other colors.