With the growth of private and public defined contribution (DC) pension plans around the world, market rates of return should increasingly play a large role in the retirement patterns of individuals. The reverse could, however, also be true - i.e., a country's population demographics could influence the financial markets. In this article, we model the potential impact of aggregate retirement patterns on macroeconomic variables with the goal of further understanding the implications of a traditional DC pension becoming the predominant source of retirement income for an entire society. We find that the economic-system feedback dampens fluctuations in the size of the working population. © 2009 The Journal of Risk and Insurance.