Real Exchange Rates and Primary Commodity Prices: Mussa Meets Backus-Smith

We show that explicitly modeling primary commodities in an otherwise totally standard incomplete markets open economy model can go a long way in explaining the Mussa puzzle and the Backus-Smith puzzle, two of the main puzzles in the international economics literature.

On Market Completions Approach to Option Pricing

Option pricing is one of the most important problems of contemporary quantitative finance. It can be solved in complete markets with non-arbitrage option price being uniquely determined via averaging with respect to a unique risk-neutral measure. In incomplete markets, an adequate option pricing is achieved by determining an interval of non-arbitrage option prices as a region of negotiation between seller and buyer of the option. End points of this interval characterise the minimum and maximum average of discounted pay-off function over the set of equivalent risk-neutral measures. By estimating these end points, one constructs super hedging strategies providing a risk-management in such contracts. The current paper analyses an interesting approach to this pricing problem, which consists of introducing the necessary amount of auxiliary assets such that the market becomes complete with option price uniquely determined. One can estimate the interval of non-arbitrage prices by taking minimal and maximal price values from various numbers calculated with the help of different completions. It is a dual characterisation of option prices in incomplete markets, and it is described here in detail for the multivariate diffusion market model. Besides that, the paper discusses how this method can be exploited in optimal investment and partial hedging problems.

The Side Effects of Safe Asset Creation

We present an incomplete markets model to understand the costs and benefits of increasing government debt when an increased demand for safety pushes the natural rate of interest below zero. A higher demand for safe assets causes the ZLB to bind, increasing unemployment. Higher government debt satiates the demand for safe assets, raising the natural rate, and restoring full employment. However, this entails permanently lower investment, which reduces welfare, since our economy is dynamically efficient even when the natural rate is negative. Despite this, increasing debt until the ZLB no longer binds raises welfare when alternative instruments are unavailable. Higher inflation targets instead allow for negative real interest rates and achieve full employment without reducing investment.

The Economics of Insurance: A Derivatives-Based Approach

This article revisits the economics of insurance using insights from derivatives pricing and hedging. Applying this perspective, I emphasize the following insights applicable to insurance. First, I provide a valid justification for the use of arbitrage-free insurance premiums. This justification applies in both complete and incomplete markets. Second, I demonstrate the importance of diversifiable idiosyncratic risk for the determination of insurance premiums. And third, analyzing the insurance industry using the functional approach, I show the importance of derivatives and the synthetic construction of derivatives for reducing an insurance company's insolvency risk. Expected final online publication date for the Annual Review of Financial Economics, Volume 13 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Equilibrium Tax Rates under Ex-ante Heterogeneity and Income-dependent Voting

The standard models with incomplete markets (e.g. Aiyagari) have difficulty justifying the current income tax rates as an optimal or political equilibrium outcome. Given the highly skewed income distribution, the majority of the population would be in favor of raising taxes to a much higher level. We show that incorporating (i) the ex-ante heterogeneity of earnings and (ii) income-dependent voting behavior helps us to reconcile the large gap between the model and data.

Keynesian Production Networks and the COVID-19 Crisis: A Simple Benchmark

The COVID-19 crisis is a seemingly all-encompassing shock to supply and demand. These negative shocks affected industries differently: some switched to remote work, maintaining employment and production, while others reduced capacity and shed workers. We consider a stripped-down version of the model in Baqaee and Farhi (2020). The model allows for an arbitrary input-output network, complementarities, incomplete markets, downward wage rigidity, and a zero lower bound. Nevertheless, the model has a stark property: factor income shares at the initial equilibrium are global sufficient statistics for the production network, clarifying assumptions that must be broken if the network is to matter.