Mary Amiti, Matthieu Gomez, Sang Hoon Kong, and David E. Weinstein

During 2018-19, the U.S. levied import tariffs of 10 to 50 percent on more than $300 billion of imports from China, and in response China retaliated with high tariffs of its own on U.S. exports. Estimating the aggregate impact of the trade war on the U.S. economy is challenging because tariffs can affect the economy through many different channels. In addition to changing relative prices, tariffs can impact productivity and economic uncertainty. Moreover, these effects can take years to become apparent in the data, and it is difficult to know what the future implications of a tariff are likely to be. In a recent paper, we argue that financial market data can be very useful in this context because market participants have strong incentives to carefully analyze the implications of a tariff announcement on firm profitability through various channels. We show that researchers can use movements in asset prices on days in which tariffs are announced to obtain estimates of market expectations of the present discounted value of firm cash flows, which then can be used to assess the welfare impact of tariffs. These estimates suggest that the trade war between the U.S. and China between 2018 and 2019 had a negative effect on the U.S. economy that is substantially larger than past estimates.