2MASS (upper panel) and WISE (lower panel) colours of all sources in our sample detected in both infrared surveys. Candidate TDEs are marked with red triangles. The black dashed line in the upper plot indicates the expected colours for main sequence stars, while colours to the upper right of the end of this line are typical of AGN. All the WISE colours we find are consistent with an AGN or galaxy nature, and stellar colours would lie off the plot to the bottom left.