The Bombay Stock Exchange Sensex on Thursday slipped 465.28 points to end at 27,827.53, while the National Stock Exchange Nifty fell past the benchmark 8,800 mark and closed at 8,591.25. In the afternoon trade, Sensex crashed 555 points and Nifty slipped by about 170 points after Director General of Military Operations Ranbir Singh announced that the Indian Indian Army had carried out "surgical strikes on terror launchpads" along the Line of Control early on Thursday.

The slump followed high trading in the Sensex in the morning, with a surge of more than 181 points, amid reports of the Organisation of Petroleum Exporting Countries' deal to cut production. Nifty had crossed the 8,800 mark, as well.

ICICI Bank saw the biggest drop of 3.8% after ICICI Prudential Life Insurance made a sluggish debut in the stock market, according to Hindustan Times. Sun Pharma, Adani Ports, State Bank of India and Axis Bank were among the other big losers, down more than 2%.

The Opec agreement is significant as it is the first time in eight years that the 14 nations decided to decrease production oil. High supply had pushed oil prices down to $40 a barrel earlier this year.

A member of BSE and NSE, Dipan Mehta, said, "An element of uncertainty has crept into the market. Foreign investors will also view this as an additional risk premium for putting their money into Indian market," according to NDTV. All stocks but one ended in the negative in the BSE index, Business Today reported.