Are firms or workers behind the shift away from DB pension

"One of the most striking changes in the composition of household retirement savings over the past 20 years has been the shift from defined benefit to defined contribution pension plans. Understanding the factors underlying this shift is important for determining its impact on retirement saving adequacy. Yet previous research, which has mostly focused on factors affecting all firms, such as regulation or increased longevity, has yielded little consensus. In this study we estimate the contribution of changing workforce characteristics and production environments to the shift in pension coverage. Our findings suggest that, while aggregate factors explain a large part of the movement, changes in worker demand, due to evolving workforce characteristics, also contributed notably. On the supply side, we find support for the theory that technical change has reduced the value of DB plans. These supply and demand factors are particularly important for explaining the significant variation in cross-industry trends in pension coverage"--Federal Reserve Board web site