Pacific Gas & Electric Co. (PG&E) employees work to fix downed power lines burned by wildfires in this aerial photograph taken above Santa Rosa, California, U.S., on Thursday, Oct. 12, 2017.

The company said earlier this month that it plans to file for Chapter 11 bankruptcy protection in the aftermath of the 2017 and 2018 fires.

Investigators have already determined PG&E's equipment was liable in at least 17 major wildfires in 2017 and it remains unclear whether PG&E will be found liable for November's Camp Fire. That fire killed at least 86 people and destroyed about 14,000 homes, making it the state's deadliest fire. The stock closed at $13.95 on Thursday.

PG&E shares spiked 74.6 percent Thursday after California investigators cleared the beleaguered utility company of liability in the October 2017 Tubbs Fire and said that a private electrical system was responsible.

The big move upward on Thursday leaves the company's stock down more than 67 percent over the last 12 months.

The California utility said in a court filing Wednesday that it can't afford a federal judge's order to inspect its energy grid and clear trees that could fall into its power lines, work it estimates would cost between $75 billion and $150 billion.

"PG&E would inevitably need to turn to California ratepayers for funding, resulting in a substantial increase — an estimated one-year increase of more than five times current rates in typical utility bills," it said in the filing.

The company told the U.S. District Court in San Francisco that the judge's so-called vegetation management plan would force it to dramatically increase the rates it charges customers to employ more than 650,000 full-time workers.

"The news from Cal Fire that PG&E did not cause the devastating 2017 Tubbs fire is yet another example of why the company shouldn't be rushing to file for bankruptcy, which would be totally unnecessary and bad for all stakeholders," said a spokesperson for BlueMountain Capital Management, a hedge fund that owns about 11 million shares of PG&E.

PG&E is California's largest investor-owned utility with 16 million customers across a 70,000-square-mile service area in Northern and Central California.

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