Traders are betting that Iraq's oil production will fall and disrupt the market.
The U.S. reportedly wants Maliki to step down in return for helping the Iraqi army with military force.
Video aired by Al-Arabiya television showed smoke billowing from the plant and a black flag used by ISIL flying from a building.
The U.S. government reportedly believes that the situation in Iraq will not change unless Nouri al-Maliki resigns as prime minister.
While fighting continued for control of the Baiji oil refinery, a report estimated that oil prices could rise by $15 to $20 a barrel.
As Obama held an hour-long meeting with congressional leaders on U.S. options in Iraq, administration officials joined a chorus of criticism of Maliki, faulting him for failing to heal sectarian rifts that militants have exploited.
Sunni fighters who may not have a radical Islamic agenda are joining the fray in Iraq. That has Kurdish militia commanders worried.
A lack of intelligence in Iraq present more risk than reward for possible U.S. air strikes.
A team of archaeologists surveyed the damage in Iraq after years of conflict.
Mesopotamia’s rich cultural history is a blessing and a curse as extremist groups make their way into the lucrative global antiquities market.
Basheer, just outside Kirkuk, fell to the jihadists on Wednesday, as desperate refugees turned back for home.
Another European official warns against increasing jihadist activity in Europe.
British Prime Minister David Cameron warns parliament to take Iraqi crisis seriously, or it will "come back to hit the U.K."
The terrorist group ISIS has been attacking towns along a major highway in Iraq since June 10, approaching the capital.
ISIS forcefully shut down Baiji refinery before taking full control of the facility, leading oil prices to climb nearly 0.5 percent.
The Iraqi prime minister also said he's trying to unite the country amid concerns of a sectarian war breaking out.
The fighters are led by the Islamic State of Iraq and Syria which aims to build a caliphate ruled on medieval precepts.
India has set up a control room to constantly monitor the situation in Iraq, and plans to send a diplomat to Baghdad.
Washington wants Maliki to do more to address the widespread sense of political exclusion among minority Sunnis in Iraq.
Hilary Clinton 2016? It's possible.
ISIS, the organization that now controls northern Iraq, was until this winter a branch of al Qaeda. How did it become so powerful?
"I would never have left," vet Mario Hernandez tells International Business Times.