Bulls hit a gusher in $OIH

Option traders have doubled their money on upside positions in the VanEck Vectors Oil Services ETF (OIH).

On Dec. 12, our Unusual Activity Service detected the purchase of 2,000 Weekly $13 calls expiring today, Jan. 3, for $0.25 as part of a bullish roll with shares at $12.83. This was clearly fresh buying, as open interest in the strike was a mere 212 contracts before that session began

Those calls have traded for as much as $0.57 today, double their purchase prics. The stock rose 5.61% in the same time period, underscoring how options can far outperform their underlying shares on a relative basis.

Long calls lock in the price where investors can buy a stock, letting them position for a rally at limited cost with the potential for significant leverage. They carry less risk than owning shares because the most that can be lost is the price of the options no matter how far the stock might fall.

OIH is currently up 1.88% at $13.57. The exchange-traded fund has rallied as the price of crude topped levels not seen since May of last year, amid geopolitical concerns.