This study proposes that heterogeneous household portfolio choices within a country and across countries offer an explanation for global imbalances. We construct a stochastic growth multicountry model in which heterogeneous agents face the following restrictions on asset trade. First, the degree of US equity market participation is higher than that of the rest of the world. Second, a fraction of households in each country maintains a fixed share of equity in its portfolios. In our calibrated model, which matches the US net foreign asset position and the equity premium, the average US household loads up more aggregate risk than the average foreign household by investing in risky assets abroad and issuing risk-free assets. As a result, the US is compensated by a high risk premium and runs trade deficits even as a debtor country. The long-run average trade deficit in our model accounts for 50% of the observed US trade deficit.