PG&E Corp's shares plunged more than 18 percent on Monday after sources said the California utility is exploring filing for bankruptcy protection as it fears a big charge in the fourth quarter related potential liabilites from wildfires.

Reuters reported on Friday the utility is considering the move for some or all of its businesses. The utility could take billions of dollars of liabilities from fatal blazes in 2018 and 2017.

Sources said a bankruptcy filing is not certain and the company could receive financial help through legislation that would let it pass on to customers costs associated with fire liabilities. But that is just a possibility, they said.

The utility said on Friday it is also looking for new directors for its holding company and its unit Pacific Gas and Electric Co.

Shares of the company (PCG.N) were trading down at $19.87 in premarket trading, its lowest since mid-November.