Does anyone know what the relevant comparison is for applying the 5% rule to the merger of defined benefit plans in the current year? Under the regulations, a merger has a "material effect" if it results or is projected to result in an increase or decrease of at least 5% in the value of assets or liabilities form the valuation date of the notice year. I expect that most mergers would increase 5% of the value of both the assets and liabilities, and therefore require an explanation. But where the plan's funding level is not changed before and after the merger (for example, the merger is between two similarly funded plans), is an explanation still required?