The stock dipped 3.28 per cent to end at Rs 571.80 on BSE. During the day, it dropped 3.54 per cent to Rs 570.25.
On NSE, shares of the company slipped 3.22 per cent to close at Rs 571.65.
In terms of equity volume, 1.85 lakh shares of the company changed hands at BSE, while over 20 lakh shares traded on NSE during the day.
Glenmark said its Baddi unit contributes approximately 10 per cent of the revenue of the US sales.
"We are in the midst of providing a comprehensive response to the observations and would be replying to the FDA shortly on the observations," it added.
The company, however, did not elaborate on the nature of observations.