Will an aging population lower stock returns?

Marginal Revolution: Will an aging population lower stock returns?: "The study, by James M. Poterba, an economics professor at the Massachusetts Institute of Technology, has found that changes in the proportion of retirees in the population have only a modest impact on stock market returns. So while the market is likely to come under some downward pressure from the retirement of boomers over the next couple of decades, he says he believes that there is no reason to expect the effects to be severe."

At face value it would appear that an aging population is likely to be a net seller of financial assets as they pass retirement age. However, there is a not a lot of empirical evidence to support this view.