An otherwise conventional Keynesian macro model is modified to include inventories of final goods by (1) drawing a distinction between production and final sales, and (2) allowing for a negative effect of the level of inventories on production. Two models are presented: one in which the labor...

I study the allocation of human capital in an economy with production externalities, financial constraints and career choices. Agents choose to become entrepreneurs, workers or financiers. Entrepreneurship has positive externalities, but innovators face borrowing constraints and require the...

The nature of the firm and its financing are closely interlinked. To produce significant net present value, an entrepreneur has to transform her enterprise into one that is differentiated from the ordinary. To achieve the control that will allow her to execute this strategy, she needs to have...

A surprisingly large amount of commentary today marks the beginning of the dot-com bubble of the late 1990s from either the Netscape Communications initial public offering of 1995 or Alan Greenspan's "irrational exuberance" speech of 1996. We believe that this is wrong: we see little sign that...

We model the relationship between asset float (tradeable shares) and speculative bubbles. Investors trade a stock with limited float because of insider lock-ups. They have heterogeneous beliefs due to overconfidence and face short-sales constraints. A bubble arises as price overweighs optimists'...

We propose a framework for understanding recurrent historical episodes of vigorous economic expansion accompanied by extreme asset valuations, as exhibited by the U.S. in the 1990s. We interpret this phenomenon as a high-valuation equilibrium with a low effective cost of capital based on...

During the Second Industrial Revolution, 1860-1900, many new technologies, including electricity, were invented. These inventions launched a transition to a new economy, a period of about 70 years of ongoing, rapid technical change. After this revolution began, however, several decades passed...

We review the evidence that artificial intelligence (AI) is having a large effect on the economy. Across a variety of statistics--including robotics shipments, AI startups, and patent counts--there is evidence of a large increase in AI-related activity. We also review recent research in this...

We study the labor markets in China and the United States, the two largest economies in the world, by examining the evolution of their cross-sectional age-earnings profiles during the past thirty years. We find that, first, the peak age in the cross-sectional age-earnings profiles, which we...

In 1961, Nicholas Kaldor used his list of six "stylized" facts both to summarize the patterns that economists had discovered in national income accounts and to shape the growth models that they were developing to explain them. Redoing this exercise today, nearly fifty years later, shows how much...