Although the aggregate capital share of U.S. firms has increased, capital share at the firm‐level has decreased. This divergence is due to mega‐firms that produce a larger output share without a proportionate increase in labor compensation. We develop a model in which firms insure workers against firm‐specific shocks, with more productive firms allocating more rents to shareholders, while less productive firms endogenously exit. Increasing firm‐level risk delays exit and increases the measure of mega‐firms, raising (lowering) the aggregate (average) capital share. An increase in the level of rents magnifies this effect. We present evidence that supports this mechanism.
