U.S. business activity in February fell to its lowest level in more than six years as companies pulled back on fears that China’s coronavirus outbreak would slow global growth, according to private survey data released Friday.

Data firm IHS Markit said its U.S. composite output index—an aggregate measure of activity in the services and manufacturing sectors—fell to 49.6 in February, down from 53.3 in January, and the lowest level since October 2013. A level below 50 indicates contraction, while a level above 50 signals expansion....