After opening on the positive note, shares of the drug firm went into a tailspin following the ban and plunged 6.35 per cent to Rs 565.60 at the BSE.
On the NSE, the stock slipped 6.42 per cent to Rs 565.50.
According to the information available on USFDA website, the regulator has issued an import alert, which enables 'detention without physical examination of drugs from firms which have not met drug GMPs'.
This is the first import alert for any of Sun Pharma's plants from the USFDA, which has been cracking down heavily on firms such as Ranbaxy and Wockhardt that have not complied with its manufacturing norms.