The oldest members of the baby boomer generation are turning 65 this year--the official retirement age.  Not exactly the best time for a lot of new retirees to start selling off equities.  In a new Economic Letter, Zheng Liu and Mark Spiegel of the San Francisco Fed's Economic Research Department point out that "U.S. equity values have been closely related to demographic trends in the past half century." And that is cause for a little worry:

Since an individual’s financial needs and attitudes toward risk change over the life cycle, the aging of the baby boomers and the broader shift of age distribution in the population should have implications for capital markets (Abel 2001, 2003; Brooks 2002). Indeed, some studies attribute the sustained asset market booms in the 1980s and 1990s to the fact that baby boomers were entering their middle ages, the prime period for accumulating financial assets (Bakshi and Chen 1994).

However, several factors may mitigate the effects of this demographic shift. First, demographic trends are predictable and rational agents should anticipate the impact of these changes on asset demand. Consequently, current asset prices should reflect the anticipated effects of demographic changes. In addition, retired individuals may continue to hold equities to leave to their heirs and as a source of wealth to finance consumption in case they live longer than expected (e.g., Poterba 2001).

Foreign demand for U.S. equities might also reduce the downward pressure on asset prices. However, the effect is probably limited for two reasons. First, other developed nations have populations that are aging even more rapidly than the U.S. population (Krueger and Ludwig, 2007). Second, there is substantial evidence of home bias in equity holdings. Individual investors typically hold disproportionate shares of domestic assets in their portfolios. For example, in 2009, the foreign equity holdings of U.S. investors were only 27.2% of the share of foreign equities in global market capitalization. While the low level of international equity diversification is still not well understood (Obstfeld and Rogoff 2001), it suggests that foreign demand for U.S. equities is unlikely to offset price declines resulting from a sell-off by U.S. nationals.

Read Boomer Retirement: Headwinds for U.S. Equity Markets? here.