Nilekani had also said the audit committee has retained law firm Shardul Amarchand Mangaldas & Co to conduct an independent investigation into the issue. In the letter, dated September 20 and signed by 'Ethical Employees', it was alleged that CEO Salil Parikh as well as Chief Financial Officer Nilanjan Roy engaged in forced revenue recognition from large contracts not adhering to accounting standards. The letter, addressed to the board, claimed that recent big deal wins carried negligible margins and that Roy directed certain people to make wrong assumptions to show margins. On Tuesday, shares of Infosys plunged over 16 per cent on Tuesday, wiping out Rs 53,450.92 crore from its market valuation. The scrip gained over one per cent in afternoon trade on the BSE and the NSE. US-based Rosen Law Firm has said it is preparing a class action lawsuit to recover losses suffered by Infosys investors in the US.