NBER

Ahmed Tahoun

London Business School
26 Sussex plc, Regent's Park
NW1 4SA London

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
Institutional Affiliation: London Business School

NBER Working Papers and Publications

April 2020Firm-level Exposure to Epidemic Diseases: Covid-19, SARS, and H1N1
with Tarek Alexander Hassan, Stephan Hollander, Laurence van Lent: w26971
Using tools described in our earlier work (Hassan et al., 2019, 2020), we develop text-based measures of the costs, benefits, and risks listed firms in the US and over 80 other countries associate with the spread of Covid-19 and other epidemic diseases. We identify which firms expect to gain or lose from an epidemic disease and which are most affected by the associated uncertainty as a disease spreads in a region or around the world. As Covid-19 spread globally in the first quarter of 2020, firms' primary concerns relate to the collapse of demand, increased uncertainty, and disruption in supply chains. Other important concerns relate to capacity reductions, closures, and employee welfare. Financing concerns were mentioned relatively rarely in the first quarter but appear to become a more i...
January 2020The Global Impact of Brexit Uncertainty
with Tarek Alexander Hassan, Stephan Hollander, Laurence van Lent: w26609
Using tools from computational linguistics, we construct new measures of the impact of Brexit on listed firms in the United States and around the world; these measures are based on the proportion of discussions in quarterly earnings conference calls on the costs, benefits, and risks associated with the UK's intention to leave the EU. We identify which firms expect to gain or lose from Brexit and which are most affected by Brexit uncertainty. We then estimate effects of the different types of Brexit exposure on firm-level outcomes. We find that the impact of Brexit-related uncertainty extends far beyond British or even European firms; US and international firms most exposed to Brexit uncertainty lost a substantial fraction of their market value and have also reduced hiring and investment. I...
November 2017Firm-Level Political Risk: Measurement and Effects
with Tarek A. Hassan, Stephan Hollander, Laurence van Lent: w24029
We adapt simple tools from computational linguistics to construct a new measure of political risk faced by individual US firms: the share of their quarterly earnings conference calls that they devote to political risks. We validate our measure by showing it correctly identifies calls containing extensive conversations on risks that are political in nature, that it varies intuitively over time and across sectors, and that it correlates with the firm’s actions and stock market volatility in a manner that is highly indicative of political risk. Firms exposed to political risk retrench hiring and investment and actively lobby and donate to politicians. These results continue to hold after controlling for news about the mean (as opposed to the variance) of political shocks. Interestingly, the v...

Published: Tarek A Hassan & Stephan Hollander & Laurence van Lent & Ahmed Tahoun, 2019. "Firm-Level Political Risk: Measurement and Effects*," The Quarterly Journal of Economics, vol 134(4), pages 2135-2202. citation courtesy of

November 2014The Power of the Street: Evidence from Egypt's Arab Spring
with Daron Acemoglu, Tarek A. Hassan: w20665
During Egypt's Arab Spring, unprecedented popular mobilization and protests brought down Hosni Mubarak's government and ushered in an era of competition between three groups: elites associated with Mubarak's National Democratic Party (NDP), the military, and the Islamist Muslim Brotherhood. Street protests continued to play an important role during this power struggle. We show that these protests are associated with differential stock market returns for firms connected to the three groups. Using daily variation in the number of protesters, we document that more intense protests in Tahrir Square are associated with lower stock market valuations for firms connected to the group currently in power relative to non-connected firms, but have no impact on the relative valuations of firms connecte...

Published: Daron Acemoglu & Tarek A. Hassan & Ahmed Tahoun, 2018. "The Power of the Street: Evidence from Egypt’s Arab Spring," The Review of Financial Studies, vol 31(1), pages 1-42. citation courtesy of

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