One Year of COVID: What Impact of the Pandemic on the Economic Activity of French Companies? Construction of Individual Counterfactuals and Diagnostics for 2020[Un an de crise Covid : comment évaluer l’impact de la pandémie sur l’activité économique des entreprises françaises ? Construction de contrefactuels individuels et diagnostics de l’année 2020]

We study the impact of the health crisis on the activity of more than 645,000 French companies using individual data to estimate their monthly turnover. Our microsimulation model is innovative in three ways. First, we quantify the loss of activity compared with a non-crisis counter- factual situation to rethink the consequences of the crisis taking into account companies' growth trajectories before the pandemic. Second, we estimate this shock at the individual level to study the heterogeneity of loss of business. We highlight the disparities of the shock both between and within sectors. The sector explains up to 48% of the variance of the monthly activity shocks observed in 2020, a much larger proportion than in a normal year. Finally, we identify four profiles of business trajec- tories in 2020. The industry is the primary determinant of belonging to these profiles. Conditionally to the sector, these profiles also correlate with the organisational adaptation of companies