Urban Institute projections suggest the stock market collapse will have small effects on most Americans' retirement incomes. It's estimated that 37 percent of Americans born between 1941 and 1965 owned no stocks when the market crashed in 2008 and that income from assets will account for a small share of retirement income, even for those with stocks. For most retirees, Social Security provides the majority of income. Had Social Security been invested in private accounts with equities, the impact of the crash would have been much largerpositive or negative, depending on one's birth cohort and on future market performance.