Shares of Chemours and DuPont spiked Friday after a judge ruled DuPont had to pay an additional $500,000 in punitive damages after being found liable for a man's testicular cancer.
Chemours — a DuPont spinoff — traded up about 17 percent, while DuPont had gained about 2.9 percent.
The punitive damages ruling came two days after a jury awarded a man $5.1 million.
In a statement, Chemours said the verdict "will be appealed, and there are substantial legal grounds to challenge the result. This type of litigation could take place over many years, and interim results do not predict the final outcome."
DuPont also said the verdict will be appealed, adding the verdict was the "the result of trial rulings that misrepresented the findings of an independent science panel and misled jurors about the risks of C8 exposure."