Microsoft (MSFT) is flat at $23.91 and recent trades include an Oct 25 – 27 call spread at 32 cents, 5000X on CBOE. Looks like a buyer initiating the trade and the spread has been repeated multiple times. Now volume in both contracts exceeds 9000. Another noteworthy trade in Microsoft today is a block of 9555 Jan 27.5 calls at the 44-cent ask price in afternoon trading. This morning, about 30 minutes after the bell, a block of 5,720 Jan 24 calls was bought to open at $1.60 on ISE, according to ISEE data. 81,000 call options now traded on the software giant, compared to 13,000 puts. The bullish trading comes ahead of a presentation at the Citi Global Tech Conference Tuesday at Noon ET.

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

Mariner Energy (ME) shares sank in volatile morning trading on reports of an explosion on one the company’s oil rigs in the Gulf of Mexico. ME sank to $19.62 and were recently down $1.04 to $22.31, and 13.7 percent off session lows. Meanwhile, options volume is running 145X the average daily, with about 23,000 puts and 3,190 calls traded. The top trade is a lot of 456 Sep 20 puts at 80 cents. It traded at 11:45 and thirty minutes after the news broke. 15.4K now traded and the contract is now bid at 40 cents. CNBC reports that no oil spilled as a result of the explosion and Dahlman Rose analysts say the explosion is likely a platform. Consequently, the fallout is likely to be consirably smaller. Still, implied volatility in the Houston-based oil driller is up sharply, almost 200 percent to 76.5.

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

Momenta Pharmaceuticals (MNTA) loses 14 cents to $14.76 and one strategist pays 25 cents for the Jan 10 – 12.5 (2X1) put ratio spread, 4000X on PHLX. Looks like a new position and might be a hedge. Implied volatility is flat today, but elevated at 92.

Bullish flow detected in Anadarko Petroleum (APC), with 23,850 calls trading, or 2x the recent avg daily call volume in the name. Shares are up $1.81 to $50.50 after The Australian published a story saying that APC is on BHP’s radar screen as a possible acquisition target. ‘A senior figure in the global energy industry is convinced that the “second target” for BHP is Anadarko Petroleum Corporation, telling The Australian he believed the US oil and gas independent was firmly on BHP’s radar. BHP declined to comment for this article.’ (Link). In options action, the focus is on APC Sep 50, 52.5 and 55 calls. Nov 55 calls are among the most actives as well.