PG&E Corp.’s stock

PCG, -27.48%

plunged 28% to a 7-month low in active morning trading Monday, after a court ruling that the California utility will have to face a jury trial over whether it is liable for damages from the Tubbs fire in 2017. Trading volume ballooned to 31.5 million shares, compared with the full-day average of about 6.5 million shares. The Wall Street Journal reported late Friday that although California investigators concluded that PG&E equipment didn’t spark the Tubbs fire, lawyers for insurers and victims said they can prove that it did. Separately, a judge ruled that PG&E can control its own bankruptcy exit plan. The stock has tumbled 56% year to date, while the SPDR Utilities Select Sector ETF

XLU, +0.64%

has rallied 17% and the S&P 500

SPX, +1.20%

has climbed 17%.