Nifty futures start the December series with a higher OI base of Rs 30,800 crore. Rollovers are at 79%, higher than the three-month average. Market-wide futures OI is at Rs 4.4 lakh crore, and rollovers are at 89%. Bank Nifty rollovers are at 76.8%, above the three-month average. Nuvama expects Nifty to trade in a range of 23,450-25,000 with heightened volatility.