The pharma firm's scrip ended at Rs 822.80, down 4.29 per cent on the BSE. During the day, it fell by 6 per cent to Rs 808.
At the NSE, the stock lost 4.29 per cent to Rs 821.
The stock was the biggest loser among the blue-chips on both Sensex and Nifty.
Sarabjit Kour Nangra, VP- Research (Pharma), Angel Broking said it is learnt that Sun Pharma's manufacturing facility in Halol (Gujarat) is undergoing a surprise inspection by the US Food and Drug Administration (US FDA). The move may have been triggered by a number of recent recalls from the plant, sources, familiar with the development."