Accreted mass fraction as a function of total stellar mass for ETGs. The measurements for NGC 5018, NGC 1533, and IC 1459 (from the three-components fit) are given as red circles. Black circles correspond to other BGGs/BCGs from the literature (Seigar et al. 2007; Bender et al. 2015; Iodice et al. 2016, 2017b; Spavone et al. 2017b, 2018). The region within the red dashed lines and the grey filled circles corresponds to the predictions of cosmological galaxy formation simulations by Cooper et al. (2013, 2015). The regions brackets by the blue continuous and dashed lines indicate the accreted mass fraction measured in the Illustris simulations by Pillepich et al. (2018, see their Fig. 12) within 30 kpc and outside 100 kpc, respectively. Magenta filled circles show the mass fraction associated with the streams from Table 1 in Cooper et al. (2015).