Cambridge Analytica's use of "psychographic" voter information was neither novel nor measurably effective, experts in the field tell NBC News.
Cambridge Analytica CEO Alexander Nix has been suspended, the company announced.
The UK's data regulator is looking at whether Facebook responded "robustly" to reports that Cambridge Analytica gained access to data on 50 million users.
#WheresZuck and other major questions hit Facebook
"It doesn't have to be true, it just has to be believed."
Alexander Nix may have misled a U.K. probe when he said his company had "never worked for Russia" or used data harvested from millions of Facebook users.
Facebook did not mention the Trump campaign or any political campaigns. It said data privacy policies had been violated.
Stephen Hawking, a British theoretical physicist who became a household name, died at the age of 76.