Optical/UV versus X-ray (0.1−500 keV) logarithmic fluxes along the outburst of Swift J0243.6+6124. The correlations show different slopes during the outburst rise than during the decay epochs for the filters with longer wavelengths (V-Johnson to UVOT-uw1). In this case, different fits have been performed for the rise (blue line) than for the decay (red line). For the UVOT-um2 and UVOT-uw2 filters, a global fit (purple line) has been performed.