Restrictions that general equilibrium theory place upon average returns are found to be strongly violated by the U.S. data in the 1889–1978 period. This result is robust to model specification and measurement problems. We conclude that equilibrium models which are not Arrow-Debreu economies are needed to rationalize the large average equity premium that prevailed during the last 90 years.

The difference between average borrowing and lending rates in the United States is over 2 percent. In spite of this large difference, there is over 1.7 times GNP in 2007 of intermediated borrowing and lending between households. In this paper a model is developed consistent with these facts. The only difference within an age cohort is preferences for bequests. Individuals with little or no bequest motive are lenders, while individuals with strong bequest motive are borrowers and owners of productive capital. Given no aggregate uncertainty, the return on equity is the same as the household borrowing rate. The government can borrow at the household lending rate, so there is a 2 percent equity premium in our world with no aggregate uncertainty. We examine the distribution and life cycle patterns of asset holding and consumption and find there is large dispersion in asset holdings and little in consumption.

This paper was subsequently published as Working Paper 685 under the title "Costly Financial Intermediation in Neoclassical Growth Theory."

There is a large amount of intermediated borrowing and lending between households. Some of it is intergenerational, but most is between older households. The average difference in borrowing and lending rates is over 2 percent. In this paper, we develop a model economy that displays these facts and matches not only the returns on assets but also their quantities. The heterogeneity giving rise to borrowing and lending and differences in equity holdings depends on differences in the strength of the bequest motive. In equilibrium, the lenders are annuity holders and the borrowers are those who have equity holdings, who live off its income when retired, and who leave a bequest. The borrowing rate and return on equity are the same in the absence of aggregate uncertainty. The divergence between borrowing and lending rates can thus give rise to an equity premium, even in a world without aggregate uncertainty.

The neoclassical growth model is extended to include costly intermediated borrowing and lending between households. This is an important extension as substantial resources are used in intermediating the large amount of borrowing and lending between households. In 2007, in the United States, the amount intermediated was 1.7 times GNP, and the resources used in this intermediation amounted to at least 3.4 percent of GNP. The theory implies that financial intermediation services are an intermediate good and that the spread between borrowing and lending rates measures the efficiency of the financial sector.