In a statement Wednesday, CAL Fire said it "has determined that the Camp Fire was caused by electrical transmission lines owned and operated by Pacific Gas and Electricity (PG&E) located in the Pulga area."
PG&E filed for bankruptcy earlier this year because it was likely to face billions of dollars in liability claims stemming from the fire.
Shares ended Wednesday off 30 cents at $18.06.
PG&E is expected to report earnings of $1.00 a share on sales of $4.4 billion for the current quarter, based on a FactSet survey of 7 analysts. In the same period a year ago, the company posted earnings of $1.16 a share on sales of $4.2 billion.The stock has fallen 12.4% since the company last reported earnings on May. 2.
PG&E is currently trading at a price-to-forward-earnings ratio of 4.6 based on the 12-month estimates of 13 analysts surveyed by FactSet.