In the presence of aggregate demand spillovers, an imperfectly competitive form's profit is positively related to aggregate income, which in turn rises with profits of all firms in the economy. This pecuniary externality makes a dollar of a firm's profit raise aggregate income by more than a dollar since other firms' profits also rise, and in this way gives rise to a "multiplier." Since such multipliers are ignored by firms making investment decisions, privately optimal investment decisions under uncertainty will not in general be socially optimal. Under reasonable conditions, investment is too low.

We investigate the relationship between management ownership and market valuation of the firm, as measured by Tobin's Q. In a 1980 cross-section of 371 Fortune 500 firms, we find evidence of a significant nonmonotonic relationship. Tobin's Q first increases, then declines, and finally rises slightly as ownership by the board of directors rises. For older firms, there is evidence that Q is lower when the firm is run by a member of the founding family than when it is run by an officer unrelated to the founder.

In the presence of aggregate demand spillovers, an imperfectly competitive form's profit is positively related to aggregate income, which in turn rises with profits of all firms in the economy. This pecuniary externality makes a dollar of a firm's profit raise aggregate income by more than a dollar since other firms' profits also rise, and in this way gives rise to a "multiplier." Since such multipliers are ignored by firms making investment decisions, privately optimal investment decisions under uncertainty will not in general be socially optimal. Under reasonable conditions, investment is too low.