When a takeover is announced, the sum of the stock-market values of the firms involved often falls, and the value of the acquirer almost always does. Does this mean that takeovers do not raise the values of the firms involved? Not necessarily. We set up a model in which the equilibrium number of...

Since 1968, the ratio of stock market capitalization to GDP has varied by a factor of 5. In 1972, the ratio stood at above unity, but by 1974, it had fallen to 0.45 where it stayed for the next decade. It then began a steady climb, and today it stands above 2. We argue that the IT revolution was...

This paper extends Lucas (1978) to a production economy with two capital goods. It is an RBC model in which each unit of investment requires a new idea, an "option". When options are scarce, new capital is harder to put in place and the value of old capital rises. Thus the stock market and...

In a model with multiple Pareto-ranked equilibria we add trade in assets that pay based on the realization of a sunspot. Asset trading restricts the equilibrium set in a way that raises welfare by eliminating equilibria with a high likelihood of disasters. When the probability of a disaster is...

The prospect of capital obsolescence inhibits investment. Investors thus become more optimistic when the obsolescence of their capital slows down. We propose a model with no fixed costs of investment, and random technological progress that induces obsolescence of capital in place. Spikes occur...

We study the effects of parameter uncertainty prompted by structural breaks. In our model, agents respond differently to uncertainty prompted by regime shifts in shock processes than they react to comparable perceived increases in shock volatility. The magnitude of the response to an increase in...

We study private equity in a dynamic general equilibrium model and ask two questions: (i) Why does the investment of venture funds respond more strongly to the business cycle than that of buyout funds? (ii) Why are venture funds returns higher than those of buyout? On (i), venture brings in new...

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...

We provide a model that links the high return to venture equity to the impatience of the VCs. VCs are scarce, and hence, they have market power and a high return on their investments. As a result, VCs are eager to terminate non-performing ventures so they can move on to new ones. The scarcity of...