Since the BP (NYSE: BP) Deepwater Horizon spill last April, oil majors have been dumping assets quicker than you can say "blowout preventer valve."

As Wall Street took a harder look at all the major oil players, big companies like ExxonMobil (NYSE: XOM) and ConocoPhilips (NYSE: COP) realized that the markets were no longer accounting value for some of their long-held assets. Thus, they began a massive divesture of a variety of oil and gas fields.

Let the games begin!
In 2010, asset sales by the world's largest oil companies exceeded $50 billion -- the most in more than 10 years. Besides a renewed spotlight on the big players, other drivers included stable oil prices, an influx of medium-sized companies willing to buy, and an overall shortage of skilled workers needed to staff and develop oil fields.

So far, BP has sold off more than $22 billion in assets; ExxonMobil divested a ton of Gulf of Mexico assets last year for about $1 billion, with many of those sales going to Energy XXI (Nasdaq: EXXI); and ConocoPhilips sold off about $4.7 billion of its projects in the Alberta tar sands. Royal Dutch Shell (NYSE: RDS-A) has become equally aggressive, selling a piece of its Texas gas fields to Occidental Petroleum (NYSE: OXY) for $1.8 billion. The bigs are trying hard to shed the long-held notion that there is little growth left in their game plans, getting rid of old or stagnating fields and putting the money to better use.

So what's the better bet?
On the surface, it looks like the big players are getting much more for their assets than analysts previously anticipated, freeing up cash for new explorations and development. This means that companies like ExxonMobil have much more potential for investor reward, but it also means more risk. However, that risk is probably well worth it -- most of the bigs have only seen share appreciation between 5% and 30% over the last five years. That doesn't sound too bad, but compare it to companies like Kodiak Oil & Gas, which has seen a 70% gain, or Apache, with its 80% gain, and the contrast is pretty stark.

It's true that these aren't necessarily fair comparisons; ExxonMobil is a $390 billion company, while Kodiak is a $930 million company. Obviously, the risk-reward scenario will be much different. Now that the big players are divesting assets to try and attain more growth moving forward, and the smaller guys are grabbing up those assets, investors must decide which of the two will be the better option to pursue.

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Jordan DiPietro owns no shares mentioned above. The Fool owns shares of ExxonMobil. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.