At the NSE, the stock slumped 32.57% to Rs. 308.25.
Following a massive sell-off in the stock, the market value of the company dipped by Rs. 5,159 crore to Rs. 14,187 crore.
According to media reports, the US Food and Drug Administration (USFDA) has issued an import alert on Ranbaxy Laboratories 's Mohali Unit.
The company in May had agreed to pay a hefty $500 million to settle charges over its adulterated drugs.
Meanwhile, in the broader market, the benchmark Sensex was trading at 19,934.77, up 202.01 points in late morning trade.