Exelon (EXC) is down $1.36 to $42.01 on an analyst downgrade and some players seem to be bracing for additional losses in the Chicago-based utility. About 10,000 puts and 7,135 calls traded on the stock so far. January 40 puts, which are 4.8 percent out-of-the-money and expiring in 17 days, are the most actives. 3,939 traded (92 percent Ask). Jan 41 puts are also trading at the offer. Meanwhile, Jan 42.5 and April 42 calls are the next most actives and trading predominantly on the bid. Implied volatility in EXC jumped 20 percent to 19 after Macquarie analysts downgraded the stock to Neutral from Outperform. Firm cites lower prices, driven by falling natural gas and coal prices, and lower demand for the downgrade.

*Scanning all single-stocks subject to 2500 contracts minimum call or put volume

Largest implied vol mover today is Spreadtrum Communications, where 30day ATMIV is up nearly 20pts to the 90% level as shares trade down about 7% near 19.46. Option flow in the fabless semiconductor firm is running triple normal levels, and puts dominate the activity with a buyer paying 85cents for Jan 17.5 puts to open a new position struck 9% out of the money and expiring in 18days. Earnings not due till March.

*Scanning all single-stocks subject to 2500 contracts minimum call or put volume

JP Morgan (JPM) adds $1.52 to $34.77 and is one of 27 Dow stocks holding gains Tuesday morning. Recent options trades on the bank include a 10000-contract block of Feb 27 puts bought for 23 cents per contract. The trade might close a position opened on 12/16 when one strategist sold 10,000 Feb 27 puts on the stock at 71 cents to buy 5,000 Feb 33 calls for $1.78. Shares are up 7.7 percent since that time and, while the puts are being bought to close, the Feb 33 calls are apparently being left open. Weekly (1/6) 35 and 36 calls on JPM are seeing interest as well. 43,000 calls and 21,000 puts total and implied vols are down 6 percent to 36. Bullish trading in JP Morgan comes ahead of a Jan 13, 2012 earnings report.