Williams Companies (WMB) is off 12 cents to $29.34 and levels of implied volatility in the options on the stock are moving higher today ahead of earnings. The natural gas producer reports after the closing bell. The top trade on the stock so far is Mar 29 – 31 bearish risk-reversal for 6 cents, 2700X on ISE. Data indicate calls were sold to buy puts and open a new position. Beyond that, the action has been in smaller lots and players are also taking positions in Mar 30 calls, which were active yesterday (see 2/21 color) and have traded 4,270 contracts today. Meanwhile, impled volatility in the options on WMB is on the move — up 18.5 percent to 27. The stock sometimes sees volatility around profit reports. The average daily post-earnings moves over the past four quarters is 5.8 percent, including a 10 percent slide on 8/4/2011.