Conspiracy theorist Alex Jones has been ordered to pay $965m (£869m) in damages after falsely claiming the 2012 Sandy Hook school shooting was a hoax.
The families of eight victims, and an FBI agent who responded to the attack, had sought at least $550m in the defamation trial in Connecticut.
They alleged the right-wing radio host’s misinformation led to a decade of harassment and death threats.
Twenty children and six adults were killed at Sandy Hook Elementary School.
Jones, who founded the conspiracy-laden Infowars website and talk show, argued for years that the massacre was a “staged” government plot to take guns from Americans and that “no-one died”.
He called the parents of victims “crisis actors” and argued that some of them never actually existed.
As the verdict was read out on Wednesday in Waterbury, Connecticut – some 20 miles (32 km) from the site of the 2012 shooting – many of the families were visibly emotional with some in tears.
The three-week trial was marked by emotional testimony from a succession of parents.
Some described receiving a deluge of online hate and others said they had to move homes repeatedly for their own safety. A father, Mark Barden, recounted hearing that people were desecrating his son Daniel’s grave by “urinating on it and threatening to dig it up”.
Jurors also heard evidence that Jones and his company, Free Speech Systems, made millions of dollars selling nutritional supplements, survival gear and other products on the Infowars catalogue.
Jones broadcast himself watching Wednesday’s verdict and scoffing at the court proceedings. He also appealed to his followers to make urgent donations, and pledged that the money would not be used towards his legal costs.
His lawyer Norm Pattis told reporters that they will appeal the decision.
“Candidly, from start to finish, the fix was in in this case,” he said outside the court.