The purpose of this paper is to examine why financial sector growth harms real growth. We begin by constructing a model in which financial and real growth interact, and then turn to empirical evidence. In our model, we first show how an exogenous increase in financial sector growth can reduce total factor productivity growth.2 This is a consequence of the fact that financial sector growth benefits disproportionately high collateral/low productivity projects. This mechanism reflects the fact that periods of high financial sector growth often coincide with the strong development in sectors like construction, where returns on projects are relatively easy to pledge as collateral but productivity (growth) is relatively low.
Next, we introduce skilled workers who can be hired either by financiers to improve their ability to lend, increasing financial sector growth, or by entrepreneurs to improve their returns (albeit at the cost of lower pledgeability). We then show that when skilled workers work in one sector it generates a negative externality on the other sector. The externality works as follows: financiers who hire skilled workers can lend more to entrepreneurs than those who do not. With more abundant and cheaper funding, entrepreneurs have an incentive to invest in projects with higher pledgeability but lower productivity, reducing their demand for skilled labour. Conversely, entrepreneurs who hire skilled workers invest in high return/low pledgeability projects. As a result, financiers have no incentive to hire skilled workers because the benefit in terms of increased ability to lend is limited since entrepreneurs’ projects feature low pledgeability. This negative externality can lead to multiple equilibria. In the equilibrium where financiers employ the skilled workers, so that the financial sector grows more rapidly, total factor productivity growth is lower than it would be had agents coordinated on the equilibrium where entrepreneurs attract the skilled labour. Looking at welfare, we are able to show that, relative to the social optimum, financial booms in which skilled labour work for the financial sector, are sub-optimal when the bargaining power of financiers is sufficiently large.Maybe the lesson is that finance departments should subsidize physics/chemistry/engineering departments.