The logo of Nike (NKE) is seen in Los Angeles, California, United States Photograph:( Reuters )
Williamson was injured when his Nike sneaker split during a game.
Nike's shares were set to come under pressure on Thursday after emerging basketball star Zion Williamson was injured when his Nike sneaker split during a game.
US TV sports broadcasts zoomed in on the incident in the college basketball game between Williamson's Duke team and North Carolina. Williamson appeared to suffer a knee injury.
"We are obviously concerned and want to wish Zion a speedy recovery," Nike said in a statement.
"The quality and performance of our products are of utmost importance. While this is an isolated occurrence, we are working to identify the issue."
While Nike shares were not yet open for formal trading on the New York stock market, its relatively thinly-traded shares on the Frankfurt market fell around 1per centt, while shares in rivals Adidas and Puma edged up.