In a world of certainty, the design of environmental policy is relatively straightforward, and boils down to maximizing the present value of the flow of social benefits minus costs. But the real world is one of considerable uncertainty -- over the physical and ecological impact of pollution,...

We re-examine the basic investment problem of deciding when to incur a sunk cost to obtain a stochastically fluctuating benefit. The optimal investment rule satisfies a trade-off between a larger versus a later net benefit; we show that this trade-off is closely analogous to the standard...

I study irreversible investment decisions when projects take time to complete, and are subject to two types of uncertainty over the cost of completion. The first is technical uncertainty, i.e., uncertainty over the amount of time, effort, and materials that will ultimately be required to...

The present value model relates an asset's price to the sum of its discounted expected future payoffs. I explore the limits of the model by testing its ability to explain the pricing of storable commodities. For commodities the payoff stream is the convenience yield that accrues from holding...

In merger analysis and other antitrust settings, risk is often cited as a potential barrier to entry. But there is little consensus as to the kinds of risk that matter - systematic versus non-systematic and industry-wide versus firm-specific - and the mechanisms through which they affect entry....

I examine the risk/return tradeoff for environmental investments, and its implications for policy choice. Consider a policy to reduce carbon emissions. To what extent does the value of such a policy depend on the expected future damages from global warming versus uncertainty over those damages,...