GlaxoSmithKline has secured a High Court injunction to prevent animal rights extremists from publishing details of its shareholders, according to reports.
The action from the pharmaceuticals giants makes it illegal for campaigners to carry out a threat to list on a website the names of people who refuse to sell their shares.
Glaxo said around 50 shareholders had been targeted over its continued use of medical research group Huntingdon Life Sciences (HLS).
The blue-chip company said letters had been sent that urged them to sell Glaxo shares or face their personal details being posted on a website.
The letter came from a group claiming to have been set up "to hold Huntingdon Life Sciences accountable for its acts of animal cruelty".
HLS is based in Cambridgeshire and has long been targeted by fanatics who want it shut down because it is involved in animal testing.
In a letter dated May 1, the extremists warned Glaxo shareholders: "Should you choose not to sell your shares within the next 14 days your details will be published, and within weeks a website will be hosted with all remaining shareholders listed."
Glaxo condemned the letter and said a police investigation was under way.
It is not the first time fanatics have targeted companies or people with links to HLS.
In June last year, Canaccord Capital quit as broker to drug maker Phytopharm after an incendiary device exploded under the car of its European finance chief.
And in 2001, John Ablewhite served nine months in prison for attacking the home of Leonard Cass, the brother of HLS managing director Brian Cass.
Last month, Ablewhite was one of four activists who pleaded guilty to a long-running terror campaign against a guinea pig farm which culminated in the theft of pensioner Gladys Hammond's body from her grave.
Glaxo said it would continue to work with HLS "as long as they continue to meet their current high standards of animal welfare in line with Home Office requirements".Reuse content