(30)To address risks at investment firm only group level, the prudential consolidation method required by Regulation (EU) 2019/2033 should in the case of investment firm only groups be accompanied by a group capital test for simpler group structures. The determination of the group supervisor, however, should in both cases be based on the same principles that apply in the case of supervision on a consolidated basis under Directive 2013/36/EU. To ensure proper cooperation, core elements of coordination measures, and in particular information requirements in emergency situations or cooperation and coordination arrangements should be similar to the core elements of coordination applicable in the context of the single rulebook for credit institutions.