Also, the drug maker is being moved out of the National Stock Exchange's CNX Nifty Junior index, which stoked selling pressure, brokers said.
Shares of Ranbaxy tanked 4.15 per cent to settle at Rs 602.65 on the BSE. In intra-day, it tumbled 5.11 per cent to Rs 596.60.
At the NSE, it closed 4.85 per cent lower at Rs 598.55.
The company's market valuation fell by Rs 1,072.11 crore to Rs 25,586.89 crore.
More From This Section
As per the lawsuit filed in the US District Court of Columbia the company "seeks immediate judicial review" of a November 4 decision of the US Food and Drug Administration (USFDA) that stripped Ranbaxy of "its statutory rights" and "literally hundreds of millions of dollars in anticipated revenues for certain generic versions of the brand-name drugs Nexium and Valcyte".
While revoking Ranbaxy's approval for the two drugs, the USFDA had cited adverse compliance status of Ranbaxy's Paonta and Dewas facilities and it was "accordingly ...Correcting its mistake and rescinding the tentative approval letters issued regarding these ANDAs".
The changes have been made on "account of proposed scheme of amalgamation with Sun Pharmaceuticals Industries Ltd," as per the changes announced yesterday by India Index Services & Products Ltd (IISL), a subsidiary of NSE Strategic Investment Corporation Ltd.
These changes would be effective from November 28, 2014.