Maturing defined benefit plans and newly set up defined contribution schemes may have different propensities to invest in risky assets, and thereby affecting the relative price of the assets. Looking at available data does indeed suggest many factors impacting on the asset allocation of the different types of pension schemes.
At the same time, the shift between types of pension schemes transfers the longevity risk of the individual into a future income risk for the individual. In the defined contribution pension system, a longer life can only be counterbalanced by either saving more, working longer or through unrealistically high rates of return on investments. None of these remedial options are available ex post.