"[...] large and complex financial institutions are [...] more likely to be bailed out. Moreover, authorities are found to be more prone to provide support to a distressed institution which is well-connected with politicians and political parties"
At the same time, "the quality of bank assets is found not to be relevant to the bailout likelihood": https://repec.bmth.ac.uk/bam/wp/BAFES11.pdf#page=10