In models of trading with heterogeneous beliefs following Harrison‐Kreps, short selling is prohibited and agents face constant marginal costs‐of‐carry. The resale option guarantees that prices exceed buy‐and‐hold prices and the difference is identified as a bubble. We propose a model where risk‐neutral agents face asymmetric increasing marginal costs on long and short positions. Here, agents also value an option to delay, and a Hamilton‐Jacobi‐Bellman equation quantifies the influence of costs on prices. An unexpected decrease in shorting costs may deflate a bubble, linking financial innovations that facilitated shorting of mortgage‐backed securities to the collapse of prices.

Climate finance is the study of local and global financing of public and private investment that seeks to support mitigation of and adaptation to climate change. In 2017, the Review of Financial Studies launched a competition among scholars to develop research proposals on the topic with the goal of publishing this special volume. We describe the competition, how the nine projects featured in this volume came to be published, and frame their findings within what we view as a broader climate finance research program.