Nexen (NXY, news, chart, volatility) calls are usually busy today, continuing a trend started last week when shares were nearly 30% below today’s $18 level. Call buyers are focused on the 20 strike in Dec and Jan, with nearly 4000 contracts trading and implied vols lifting several points. Over the past 10days more than 10,000 of the Jan 20 calls have traded, open interest has grown by nearly 6000 contracts, and shares have recoverd from lows near $11.50 to $18. Today’s flow suggests traders are positioning for further upside, despite a recent analyst downgrade.