The UNITE trade union has condemned the loss of 200 jobs at EBS Building Society as "ripping the heart out of what was once an institution of the people".
The 200 job cuts will be split between high street branches and head office in Dublin.
UNITE said EBS was "showing disregard for the workers who built it" as well as for the customers who relied on its services.
Staff will meet union officials next Tuesday to discuss the possibility of industrial action.