“The devastating and unprecedented wildfires of 2017 and 2018 have had a profound impact on our customers, employees and communities,” the utility said. “Regardless of today’s announcement, PG&E still faces extensive litigation, significant potential liabilities and a deteriorating financial situation, which was further impaired by the recent credit agency downgrades to below investment grade.”

At least one of the company’s investors, the New York-based hedge fund BlueMountain Capital, said PG&E ought to reconsider a bankruptcy filing in light of the state’s conclusions about the Tubbs Fire. The hedge fund said earlier on Thursday that it would seek to replace PG&E’s board, which it accused of failing the company’s shareholders, customers and employees.

“The news from CalFire 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,” Omar Vaishnavi, head of fundamental credit at BlueMountain Capital, said in a statement.

Investors and analysts who are skeptical that the company needs bankruptcy argue that PG&E has access to plenty of assets it could borrow against or sell to meet its wildfire liabilities, including its headquarters building in San Francisco and its gas business. Selling such assets would still leave the company as the primary electricity utility to much of Northern and Central California.

Stocks of companies that are on the verge of filing for bankruptcy often trade for pennies because investors believe that shareholders will get wiped out in a court-ordered reorganization. The Thursday rally in PG&E’s stock could further undermine the case for a bankruptcy. The company’s stock outstanding was worth more than $7 billion at Thursday’s closing price.

But PG&E’s board might still decide to seek bankruptcy because it could conclude that is the most expedient way to resolve the thousands of wildfire claims against the utility. A filing could also protect the company in case its liabilities turn out to be much higher than current estimates.

California officials have not yet determined the cause of the November 2018 Camp Fire, the state’s most devastating. That wildfire killed at least 86 people and destroyed the town of Paradise. It could be months more before investigators reach a conclusion about its cause. Mr. Newsom said the state expected to determine the cause of the Camp Fire within the first half of the year.