In the United States, the capital share of income grew over the 1990s and 2000s and the expansion of pass-through businesses played a large role. Household survey data show business income was a primary component behind the rise in income inequality. The same data indicate households at the top of the income distribution also have a high marginal propensity to save. A model accounting for heterogeneity in saving behavior across households demonstrates the capital income shock can have a relatively large effect on the equilibrium interest rate due to the combined effect on capital demand and supply.