From Longman Business Dictionarytier 1 equityˌtier ˈ1 ˌequity [uncountable]FINANCE shareholders’ equity in a bank. By law, banks must have a minimum amount of tier 1 equity in relation to other forms of capitalThe bank currently has $8.894 billion in core equity capital, giving it a 4.08% tier 1 equity capital ratio. → equity