By Jud Pyle, CFA, chief investment strategist for

CHICAGO -- A couple months ago, we saw an investor purchase Oct. 55 calls in Exxon Mobil (XOM) - Get Report with shares trading around $71. This was presumably a bullish bet that the stock would hold its level or rally to gain leveraged exposure in the mega-cap stock. Yesterday, we saw even more bullishness in the Jan. 2010 70 call series, despite a $2.40 drop in stock since then.

Nearly 19,000 of these options traded with a volume-weighted average price of $3.85. Investors who bought these calls need XOM shares to expire higher than $73.85 in a couple months to make money. These calls closed up 35 cents and were home to open interest of 32,253 contracts. That computes to an implied volatility of 27, according to the Sidewinder report at

. Open interest of these calls currently stands at 38,730 contracts.

Shares of the world's largest company (by market value) closed up 59 cents to $68.59 on the day, and are currently up 41 cents to $69 in premarket trading. These calls had a delta of 48 cents, meaning the options should have moved 48 cents for every dollar change in the underlying. The Jan. 70 calls should have moved 23 cents, but call-buyers pushed the options up 12 cents more on the day.

Bullish call-buying such as this does not automatically mean XOM shares are poised to charge higher, but it is interesting that we saw at least one investor make a bullish bet that the stock could rally nearly 8% higher by January 2010 expiration.

Jud Pyle is the chief investment strategist for Options News Network ( and the portfolio manager of Options Alerts. Click here for a free trial for Options Alerts. Mr. Pyle writes regularly about options investing for

Jud Pyle, CFA, is the chief investment strategist for Options News Network. Pyle started his career in finance in 1994 as a derivative analyst with SBC Warburg. After four years with Warburg, Pyle joined PEAK6 Investments, L.P., in 1998 as an equity options trader and as chief risk officer. A native of Minneapolis, Pyle received his bachelor's degree in economics and history from Colgate University in 1994. As a trader, Pyle traded on average over 5,000 contracts per day, and over 1.2 million contracts per year. He also built the stock group for all PEAK6 Investments, L.P. hedging, which currently trades on average over 5 million shares per day, and over 1 billion shares per year. Further, from 2004-06, he managed the trading and risk management for PEAK6 Investments L.P.'s lead market-maker operation on the former PCX exchange, which traded more than 10,000 contracts per day. Pyle is the "Mad About Options" resident expert. He is also a regular contributor to "Options Physics."