We construct novel text-based measures of firm-level cyber risk exposure based on quarterly earnings calls of 12,000+ firms from 85 countries over 20+ years. We categorize each cyber-related discussion into topics that capture sentiment, monetary loss, country names, etc. We document new facts...

We develop a novel firm-level measure of cybersecurity risk using textual analysis of cybersecurity-risk disclosures in corporate filings. The measure successfully identifies firms extensively discussing cybersecurity risk in their 10-K, displays intuitive relations with quantitative measures of...

This paper examines the importance of buyer-supplier relationships, geography and the structure of the production network in firm performance. We develop a simple model where firms can outsource tasks and search for suppliers in different locations. Low search and outsourcing costs lead firms to...

Urban rail transit investments are expensive and irreversible. Since people differ with respect to their demand for trips, their value of time, and the types of real estate they live in, such projects are likely to offer heterogeneous benefits to residents of a city. Using the opening of a major...

New York City's multipronged subway system was a major disseminator - if not the principal transmission vehicle - of coronavirus infection during the initial takeoff of the massive epidemic that became evident throughout the city during March 2020. The near shutoff of subway ridership in...

This paper uses fare changes in Mexico City, Guadalajara, and Monterrey to estimate the price elasticity of demand for urban rail transit. In two of the cases there is a significant fare increase (30%+), and in the third there is a 60-day fare holiday. Ridership responds sharply in the expected...

The recent development of quantitative urban models provides a new set of tools for evaluating transport improvements. Conventional cost-benefit analyses are typically undertaken in partial equilibrium. In contrast, quantitative urban models characterize the spatial distribution of economic...

We investigate the relationship between the opening of a city's subway network and its air quality. We find that particulate concentrations drop by 4% in a 10km radius disk surrounding a city center following a subway system opening. The effect is larger near the city center and persists over...

We investigate the relationship between the extent of a city's subway network, its population and its spatial configuration. For the 632 largest cities in the world we construct panel data describing population, measures of centralization calculated from lights at night data, and the extent of...

While the advent of cryptocurrencies and digital assets holds promise for improving and disrupting financial systems by offering cheap, quick, and secure transfer of value, it also opens up new payment channels for cybercrimes. A prerequisite to solving a problem is understanding the nature of...