import re
string = "'Everest Re Group, Ltd. [SPB: Акции]','IHS Markit Ltd. [МБ ФР: Т+ Акции и ДР]','Invesco Ltd. [SPB: Акции]'"
re.findall(r'\[.+\]', string)
output: ["[SPB: Акции]','IHS Markit Ltd. [МБ ФР: Т+ Акции и ДР]','Invesco Ltd. [SPB: Акции]"]