By Mike Yamamoto, managing editor of OptionMonsterNEW YORK -- Spectra Energy ( SE) has been a favorite target for bulls in recent months, and on Monday they returned. OptionMonster's tracking systems found heavy buying in the December 35 calls, which saw more than 11,700 contracts trade Monday. The action was led by blocks of 4,909 and 2,853 that went for 85 cents in volume well above the strike's previous open interest of just 499 contracts, clearly showing that these are new positions. These calls lock in the price where traders can buy the stock through mid-December regardless of how far it might rise. The options could be sold earlier at a profit if premiums rise with a rally before then, but the contracts could expire worthless if shares remain below the $35 strike price. Spectra's shares slipped 0.15% to $33.49 on Monday. The natural-gas company has been falling from the $36 level since reporting second-quarter results on Aug. 6, breaking below its 50-day moving average last week. The energy name saw bullish option activity in May and June. Total option volume in Spectra surpassed 15,000 contracts Monday, quadruple its daily average for the last month, and calls outnumbered puts by a bullish 32-to-1 ratio. Yamamoto has no positions in SE.