I work with a group studying these questions in Ontario and while opinion surveys are always suspect the same findings came out of a similar study here of plan sponsor attitudes, citing volatility of costs as primary reason to close off a plan, especially among mature plans. That doesnt fully explain the decline though - plans had mature populations and liabilities before the current era and did not drop the plans, and it doesnt explain the lack of new plan starts (it does suggest a lack of ability by management to properly run investment funds)...others have pointed to the shift of decision-making from HR to CFO offices, and the greater focus on pensions as balance sheet liabilities, which are then dealt with as risk not at essential HR policies, however, other have pointed out that plenty of risk-based balance-sheet compensation is doled out by sponsors - cf. stock options. The usual conclusion is that it is just another form of depressing wages, in this case, deferred wages...but am interested in work on the causes of decline that folks are aware of...thanks in advance.