Long calls have been growing in popularity on Whiting Petroleum Corp (WLL) in recent weeks
Although crude oil is extending its recent slide, shares of energy issue Whiting Petroleum Corp (NYSE:WLL) are up 6.4%% to trade at $40.02. Against this backdrop, calls are crossing the tape at four times what's typically seen at this point in the day, and are outpacing puts by a more than 3-to-1 margin. Short-term contracts are in high demand, as well, per WLL's 30-day at-the-money implied volatility, which has popped 10.1% to 91.1% -- in the 98th percentile of its annual range.
Diving deeper, the equity's weekly 3/27 40-strike call has seen the most action, with all signs suggesting buy-to-open activity -- a theory echoed by data from the International Securities Exchange (ISE). By purchasing new positions here, traders are betting on WLL to extend its lead north of the round-number $40 mark through next Friday's close, when the weekly series expires. Amid today's surge, delta on the call has risen to 0.55 from 0.41 at last night's close, suggesting an increased probability of an in-the-money finish.
Widening the sentiment scope reveals traders have shown a growing affinity for long calls over puts in recent weeks. At the International Securities Exchange (ISE), Chicago Board Options Exchange (CBOE), and NASDAQ OMX PHLX (PHLX), WLL's 10-day call/put volume ratio has jumped to 2.08 from 0.70 over the past two weeks. What's more, the current ratio ranks in the 62nd annual percentile, meaning calls have been bought to open over puts at a faster-than-usual clip. 
This optimism toward a stock that's up roughly 18% month-to-date -- mostly due to M&A rumors, which have since been squashed -- has spilled outside of the options arena, as well. Nearly 71% of covering analysts maintain a "buy" or better rating on Whiting Petroleum Corp (NYSE:WLL). However, it appears the brokerage bunch may be changing their tune, considering both Susquehanna and Global Hunter downgraded the stock yesterday.