Radial distributions of the stacked GCs for the UDGs in our HST sample. Top: radial distribution of the stacked GCs for all 74 UDGs in our sample. The black squares are for the GC counts within 2R_e while the red squares are the counts outside (background). The counts are also shown with the detection corresponding to the candidate nucleus (or nuclei, in the case of MATLAS-138 and 987) in each galaxy removed (grey points and dotted line). The Sérsic fit is shown with the dash-dot blue line. Middle: same as the top but for the nucleated UDGs only. Bottom: same as the top but for the non-nucleated UDGs only.