No previous infectious disease outbreak, including the Spanish Flu, has affected the stock market as forcefully as the COVID-19 pandemic. In fact, previous pandemics left only mild traces on the U.S. stock market. We use text-based methods to develop these points with respect to large daily stock market moves back to 1900 and with respect to overall stock market volatility back to 1985. We also evaluate potential explanations for the unprecedented stock market reaction to the COVID-19 pandemic. The evidence we amass suggests that government restrictions on commercial activity and voluntary social distancing, operating with powerful effects in a service-oriented economy, are the main reasons the U.S. stock market reacted so much more forcefully to COVID-19 than to previous pandemics in 1918–1919, 1957–1958, and 1968.

We gratefully acknowledge financial support from the U.S. National Science Foundation (SES 1324257) and the University of Chicago Booth School of Business. We thank the editor and an anonymous referee for helpful comments on an earlier draft. Data on our newspaper-based classifications of daily stock market jumps are available at https://stockmarketjumps.com. Data for our newspaper-based Equity Market Volatility Tracker and Infectious Disease Equity Market Volatility Tracker are available at http://www.policyuncertainty.com. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. At least one co-author has disclosed a financial relationship of potential relevance for this research. Further information is available online at http://www.nber.org/papers/w26945.ack NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

Raj for helpful comments. We alone are responsible for any errors and omissions. The views expressed in the article are those of the authors and do not necessarily represent the views of the institutions that the authors belong to. The article has been accepted for publication in the Journal of Investment Management. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

We examine how trade policy uncertainty is reflected in stock returns. Our identification strategy exploits quasi-experimental variation in exposure to trade policy uncertainty arising from Congressional votes to revoke China's preferential tariff treatment between 1990 and 2001. More exposed industries commanded a risk premium of 6% per year.The risk premium was larger in sectors less protected from globalization, and more reliant on inputs from China. More exposed industries also had a larger drop in stock prices when the uncertainty began, and more volatile returns around key policy dates.Moreover, the effects of policy uncertainty on expected cash-flows, investors' forecast errors, and import competition from China cannot explain our results.

We examine next-day newspaper accounts of large daily jumps in 16 national stock markets to assess their proximate cause, clarity as to cause, and the geographic source of the market-moving news. Our sample of 6,200 market jumps yields several findings. First, policy news -mainly associated with monetary policy and government spending -triggers a greater share of upward than downward jumps in all countries. Second, the policy share of upward jumps is inversely related to stock market performance in the preceding three months. This pattern strengthens in the postwar period. Third, market volatility is much lower after jumps triggered by monetary policy news than after other jumps, unconditionally and conditional on past volatility and other controls. Fourth, greater clarity as to jump reason also foreshadows lower volatility. Clarity in this sense has trended upwards over the past century. Finally, and excluding U.S. jumps, leading newspapers attribute one-third of jumps in their own national stock markets to developments that originate in or relate to the United States. The U.S. role in this regard dwarfs that of Europe and China.