The S&P BSE Sensex and NSE Nifty 50 indexes snapped their six-day winning streak led by losses in the country's second largest software services company Infosys. The Sensex fell as much as 374 points and the Nifty 50 index dropped as much as 88 points to fall below 11,600. The benchmarks opened higher but soon turned volatile and the Sensex switched direction at least 10 times before extending losses in afternoon deals. Infosys was the top drag on the benchmarks, the stock slumped the most in six years after it received anonymous whistleblower complaints alleging certain unethical practices by the company's top management.

The Sensex ended 335 points or 0.85 per cent to close at 38,964 and the Nifty 50 index declined 74 points or 0.85 per cent to settle at 11,588.

Seven of 11 sector gauges compiled by National Stock Exchange ended higher led by the Nifty Pharma index's 1.96 per cent gain. On the flipside, Nifty IT index was top losers, down 5 per cent.

Mid- and small-cap shares ended mixed as the Nifty Smallcap 100 index rose over 1 per cent while Nifty Midcap 100 index ended on a flat note.

Infosys shares dropped as much as 16.86 per cent to Rs 638.35 after the IT services company said it had received anonymous whistleblower complaints alleging certain unethical practices. While whistleblowers accused CEO Salil Parekh of leading an effort to shore up profits through irregular accounting, Infosys said one of the complaints dealt largely with allegations relating to his international travel to the US. The allegations come just two years after Infosys endured a shake-up that saw its top boss Vishal Sikka leave the company.

Infosys investors lost nearly Rs 53,000 crore after its stock saw the worst drop in over six years. At today's close Infosys' market capitalisation stood at Rs 2.74 lakh crore as against Rs 3.27 lakh crore in the previous session.

Tata Motors, Bajaj Finserv, Bharti Airtel, HCL Technologies, Tech Mahindra, Asian Paints and Tata Steel were also among teh losers.

On the flipside, Dr Reddy's Labs, ICICI Bank, Bharat Petroleum, Titan, Cipla, Coal India and Wipro were among the gainers.