Wockhardt was among the stocks that dropped on Tuesday after the Bombay Stock Exchange (BSE) stipulated that 74 stocks must be settled on a trade-to-trade basis, forcing buyers and sellers to square the trade after each transaction.
The requirement is part of surveillance measures, BSE said, while traders added that the action was likely meant to curb speculation and ensure that shares bought or sold are actually delivered.
The shares dropped as the measures would essentially curb margin-related trading on these stocks, traders said.
"Trading Members should note that the transfer of scrips for trading and settlement on a trade-to-trade basis is purely on account of market surveillance measure and it should not be construed as an adverse action against the company," BSE said in a statement.
Wockhardt dropped 5.6 percent, SKS Microfinance slumped 11 percent and Heidelberg fell 4.4 percent as of 0425 GMT.