The stock plunged 14.38 per cent to Rs 401 on the BSE.
On the NSE, shares of the company tumbled 14.77 per cent to Rs 400.10.
An inspection was conducted by the US Food & Drug Administration (USFDA) at two of its facilities recently -- the Active Pharmaceutical Ingredients (API) manufacturing facility at Manali, near Chennai, and the Pharmaceutical Formulations facility at Kothur, near Hyderabad, in early February and March respectively, Natco said in a statement yesterday.