Takeda's shares fell as much as 8.8 percent to 4,396 yen after the verdict, hitting an eight-month low and marking their biggest one-day drop in five years.
Lanier acknowledged it was not certain whether the damages award would be sustained as the legal process continued.
"Nobody has gone out and bought a new home," he told Reuters.
"This is a conservative judge and a conservative court and she's very 'balls and strikes.' We're not under any grand illusion."
Read More US court backs patent for Eli Lilly drug Alimta
He added that the judge wanted post-verdict motions filed quickly but had set no precise schedule.
Last May, a U.S. judge had nullified a separate jury verdict for $6.5 million against Takeda after ruling that the plaintiffs had failed to offer any reliable evidence that Actos had caused cancer.
In the latest case, Lanier said the jury deliberated for only an hour and 10 minutes to deliver its verdict finding liability on all 14 questions, and another 45 minutes to come out with the multibillion dollar punitive damages.
The jury also ordered the payment of $1.475 million in compensatory damages in the suit.
The case is In re: Actos product liability litigation, U.S. District Court for the Western District of Louisiana, No. 11-MD-2299.