The U.S. saw its largest ever decline in the number of business owners between February and April, as at least 3.3 million shut their doors, a new paper from the National Bureau of Economic Research using the Census Bureau’s Current Population Survey found.

What it means: The record wave of closures was widespread but disproportionately hit minority- and immigrant-owned firms, and “may portend longer-term ramifications for job losses and economic inequality,” the study found.

African American businesses were the hardest hit.