A large trade is making a long-term bullish bet on Exxon Mobil.

optionMONSTER's Heat Seeker system detected the purchase of 5,000 January 2017 85 calls were purchased in one print for $2.19 today. This is clearly a new position, as volume was well above the strike's open interest of 3,077 contracts before the trade appeared.

These long calls lock in the price where the stock can be purchased through early 2017 no matter how far it might climb. They could be sold earlier at a profit if premiums rise with a rally before then, providing potentially significant leverage, but the contracts will expire worthless if shares remain below $85. (See our Education section)

XOM is up 0.34 percent to $73.01 today but has fallen some 21 percent this year. The energy giant's next quarterly results are expected near the end of October.

Overall option volume in the name is well below it full-session average for the last month, but total calls are outpacing puts by more than 3.5 to 1 so far.

More From optionMONSTER

• Bulls go bottom-fishing in metals
  
• Notable option activity in equities
  
• Video: October put buying in VIX