Macroeconomic models with heterogeneous agents and incomplete markets (e.g. Krusell and Smith, 1998) usually assume that consumers, rather than firms, own and accumulate physical capital. This assumption, while convenient, is without loss of generality only if the asset market is complete. When financial markets are incomplete, shareholders will in general disagree on the optimal level of investment to be undertaken by the firm. This paper derives conditions under which shareholders unanimity obtains in equilibrium despite the incompleteness of the asset market. In the general equilibrium economy analyzed here consumers face idiosyncratic labor income risk and trade firms' shares in the stock market. A firm's shareholders decide how much of its earnings to invest in physical capital and how much to distribute as dividends. The return on a firm's capital investment is affected by an aggregate productivity shock. The paper contains two main results. First, if the production function exhibits constant returns to scale and short-sales constraints are not binding, then in a competitive equilibrium a firm's shareholders will unanimously agree on the optimal level of investment. Thus, the allocation of resources in this economy is the same as in an economy where consumers accumulate physical capital directly. Second, when short-sales constraints are binding, instead, the unanimity result breaks down. In this case, constrained shareholders prefer a higher level of investment than unconstrained ones.