GlaxoSmithKline (GSK) has obtained an emergency injunction against animal rights extremists who sent threatening letters to the drug group's investors.
Animal rights activists have targeted Huntingdon
The High Court injunction prevents the Campaign Against Huntingdon Life Sciences from sending more letters.
It also prevents them from carrying out a threat to publish personal details of GSK investors on the internet.
Police are investigating the campaign, while the government says it will look at ways to protect investor privacy.
GSK's chief executive, JP Garnier, said his shareholders - at least 50 of whom were sent the letters - had shown "courage, integrity and resilience" in the face of the threats.
He also described the activists as "extremists" who had behaved in "a deplorable way".
Activists have targeted animal testing firm Huntingdon Life Sciences and its business partners for years.
GSK added that it had been contacted by investors, many of them elderly, who felt "victimised" by the letters.
It has told anyone who receives threatening correspondence to keep the letters and report them to the police.
Meanwhile, to protect the privacy of its investors, GSK has advised them to transfer their shares to the GSK corporate nominee service or ask their stockbroker to hold them in a nominee account.
Stockbroker groups have denounced the campaign as "terrorism", while medical researchers have defended animal testing as a "small but vital" part of medical research which had saved millions of lives.
"We do this research to save people's lives and to prevent human suffering and we have to use animals," Research Defence Society chief executive Dr Simon Festing said.
However, animal rights groups, such as People for the Ethical Treatment of Animals, have defended the campaign.
"If you invest in a company that is involved in animal torture, then you should expect - it's a public limited company - that information is open to the public," one campaigner, John Curtin, said.
One investor who received one of the letters, former Glaxo employee James Galpin, appeared unfazed.
"It's completely the wrong target if you actually want to change what kind of testing is done on drugs," Mr Galpin said.
"Targeting one individual pharmaceutical company isn't going to do anything. You have to target the regulatory authorities."
An intimidation campaign led to Huntingdon being delisted from the London Stock Exchange, and its US parent company had its listing on the New York Stock Exchange postponed last autumn.
GSK said it would continue to work with HLS despite the threats.
"We deplore long-term campaigns of violence, intimidation and harassment against employees, their families and people associated with the company," a GSK statement said.