Capital income inequality is large and growing fast, accounting for a significant portion of total income inequality. We study its growth in a general equilibrium portfolio choice model with endogenous information acquisition and heterogeneity across household sophistication and asset riskiness. The model implies capital income inequality that grows with aggregate information technology. Investors differentially adjust both the size and the composition of their portfolios, as unsophisticated investors retrench from trading risky securities and shift their portfolios to safer assets. Technological progress also reduces aggregate returns and increases the volume of transactions, features that are consistent with recent U.S. data.