SED of the four simultaneous MAGIC/NuSTAR/Swift observations (MJD 57757, MJD 57785, MJD 57813, MJD 57840). The data points and obtained one-zone SSC models are plotted with brown markers and orange lines, respectively. The parameters of the one-zone SSC models are shown in Table 5. For comparison purposes, the one-zone SSC model of the first pointing (MJD 57757) is plotted with black dotted lines in all the other subplots. The Compton dominance parameter A_C determined from the model is indicated on each panel. Archival data representing the typical Mrk 421 state from Abdo et al. (2011) are shown in grey.