Extreme behaviour and volatility was seen in the stock markets today unlike previous trading sessions. On Wednesday, Sensex jumped by 2.06 per cent, which is 622.44 to settle at the level of 30,818.61 while, its NSE counterpart-Nifty gained by 187.45 points or 2.11 per cent more than its previous close to end the session in green at 9,066.55 level.