We model high-frequency traders in electronic markets. We ask how the presence of such middlemen may affect welfare. We find that middlemen process public information faster than the average investor. As such, they can play a positive or a negative role. On the positive side, when they enter a...

This paper develops a set of criteria for identifying the arrival of a general purpose technology (GPT) and applies them to the electification and IT "revolutions" of the late 19th and early 20th centuries. The criteria suggest that a GPT should be 1) pervasive, 2) improving over time, and 3)...

While a start-up firm waits for its sales to materialize, it is a "pre-producer". This waiting period represents a special kind of entry cost. This paper studies how such entry costs influence the several stages of an industry's life cycle. Assuming that the production hazard is rising in the...

A firm has investment options that it may use up immediately, or store for future use. A patent, e.g., is an option to implement an idea via a product or process innovation. Other investment options are protected by secrecy. An investment option is a profit opportunity that requires an...

Aside from the equilibrium that Hotelling (1931) displayed, his model of non-renewable resources also contains a continuum of bubble equilibria. In all the equilibria the price of the resource rises at the rate of interest. In a bubble equilibrium, however, the consumption of the resource peters...

Our paper shows that investment by new firms responds to Tobin's Q much more elastically than does investment by incumbent firms. To explain this fact we build a model in which the investment-supply curve of incumbent firms is highly elastic and positively related to Q. However, when variation...

Investment in reputation responds positively to news shocks and to current aggregate shocks when they are autocorrelated. Idiosyncratic risk is contractionary and reduces the response to aggregate shocks. In this sense the rise in idiosyncratic risk can explain the great moderation -- the two...

"This paper studies optimal investment policies when the production function depends on capital of various vintages. In such an environment it is natural to ask whether the firm will invest in old-vintage capital at all. In this paper I derive such a condition. Predictably, investment in old...