A US jury in Louisiana has ordered Japanese firm Takeda Pharmaceutical to pay $6bn (£3.6bn) in punitive damages, over claims it was hiding cancer risks associated with diabetes drug Actos.
US firm Eli Lilly, a co-defendant in the case, has been ordered to pay $3bn in punitive damages.
Takeda's shares fell by about 9%, their biggest drop in five years, following the ruling.
The drugmaker said it "respectfully disagrees with the verdict".
Earlier this week, the same jury awarded $1.5m in compensatory damages to plaintiff Terrence Allen.
In his lawsuit, Mr Allen alleged that Takeda was aware of the link between Actos and bladder cancer early in the decade, but chose to withhold the information from consumers and the healthcare industry.
Mr Allen was diagnosed with bladder cancer in January 2011. He was using the Actos drug from 2004 to 2011.
In a statement, Takeda said it intended to "vigorously challenge this outcome through all available legal means, including possible post-trial motions and an appeal".
"We have empathy for the Allens, but we believe the evidence did not support a finding that Actos caused his bladder cancer. We also believe we demonstrated that Takeda acted responsibly with regard to Actos."
Mr Allen's lawyer, Mark Lanier, has acknowledged he is uncertain whether the damages will be upheld.
He said: "No one has gone out and bought a new home. We're not under any grand illusion."
Mr Allen's case is the first of more than 2,500 Actos lawsuits pending in the US federal court system, which all involve similar allegations that Takeda Pharmaceuticals failed to give adequate warnings to users or the medical community about the risk of bladder cancer from Actos.
In May 2013, a California jury awarded $6.5m in damages over claims of an Actos-related bladder cancer. But a judge reversed the verdict later and threw out the claim.
Takeda started selling Actos in the US in 1999. US firm Eli Lilly and Takeda co-promoted Actos from 1999 to 2006.
According to court documents, Actos has generated more than $16bn in sales since 1999.
The US Food and Drug Administration (FDA) announced in 2011 that using Actos for more than one year could be associated with an increased risk of bladder cancer.
Governments in France and Germany banned Actos after the FDA's announcement.