Our post-maximum spectra of SN 2009dc, with days relative to maximum light indicated for each spectrum. Important features discussed in the text are labelled. All spectra have been dereddened by E(B−V)MW = 0.070 mag and E(B−V)host = 0.1 mag with RV = 3.1. We have also removed the host-galaxy recession velocity (cz = 6300 ± 300 km s−1).