The Covid-19 economic shutdown has hurt African American businesses the most among racial and ethnic groups in U.S., with a 41% decline of black owners from February to April, a new study from the National Bureau of Economic Research shows.

While the pandemic has hit entrepreneurs across the board, closing some 3.3 million small businesses at least temporarily, the sidelining of 440,000 African Americans was especially severe. Black owners may have fared worse because fewer of them operated in industries deemed “essential” during the pandemic, among other factors, according to the NBER paper. Immigrant business owners also fared poorly, with a 36% drop during the period.