The largest oil company in the world isn't ExxonMobil (NYSE:XOM). In fact, the company isn't even close compared to the state-controlled national oil companies. These companies have been known for two things: producing massive amounts of oil and being untouchable for outside investors. That trend is starting to fade, though, as several of the large national oil companies are starting to open up more to the public.

The most recent example of this is Mexican oil company PEMEX. The Mexican government is going so far as to change the country's constitution in order to adjust the rules governing the oil industry so that PEMEX can more openly engage with other companies. The question remains, though, as to why these national oil giants are turning away from their old ways and embracing the global market. Tune in to the video below where Fool.com contributor Tyler Crowe takes a look at some of the recent moves by national oil companies and asks why they are making these moves today.

Fool contributor Tyler Crowe has no position in any stocks mentioned. You can follow him at Fool.com under the handle TMFDirtyBird, on Google +, or on Twitter: @TylerCroweFool.

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