On the eve of the takeover bid, Valeant and Ackman disclosed that they established a joint venture to make the offer, with Ackman said that Pershing Square had acquired 28.9 million shares of Allergan, or 9.7% of the company.
Valeant, headquartered in Laval, Quebec, says the acquisition will enable huge cost savings and create a leader in opthalmology, dermatology, aesthetics and other growing health fields.
Under the terms of the proposal, Valeant would buy each Allergan share for $48.30 in cash plus 0.83 shares of Valeant, saying the bid represented a "substantial" premium to Allergan's valuation.
Allergan shares fell 1.0% to $159.65 and Valeant shares dropped 0.9% to $129.98% in late-afternoon trade in New York.
Copyright Agence France-Presse, 2014