BP shares appear set for their worst one-day fall since 2010 after a judge ruled the oil company had been negligent in events leading up to the 2010 Gulf of Mexico oil spill.
The company's shares were down by 6% at the close of trading in London - making it the worst performer on the FTSE 100.
The ruling could add billions of dollars in fines to the more than £25 billion the company has already been charged for the disaster.
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Guillier conceded a "severe defeat" defeat to his supporters as the result came in.
The outage struck Hartfield-Jackson Atlanta International Airport at around 1pm local time, stopping all outgoing flights.
It will be a chilly day for many parts with the highest temperatures, about 10 Celsius (50F) in the far northwest.