NEW YORK ( TheStreet) -- Activist investor William Ackman is at it again.
This time he has joined forces with Valeant Pharmaceuticals ( VRX) for a hostile takeover of Allergan ( AGN), the maker of the plastic surgeon's friend, Botox, according to filings on Monday.
Ackman got involved in the move to acquire Allergan, worth around $42 billion, after Valeant's unsuccessful efforts over the past year. Adding Ackman and his $13 billion Pershing Square Capital to the mix ratchets up the pressure on Allergan.
Valeant shares, recently at around $132, are up 12.6% year to date. That includes a 5% gain today.
Shares of Allergan, trading recently at about $164, are up 47% so far this year, including a 15% gain today on news of the deal.
Any deal between Allergen and Valeant would bring together two mid-sized pharmaceutical companies that specialize in skin-care and eye-care products.
Valeant has been on a buying spree recently, acquiring Bausch & Lomb Holdings last May, for instance. The Canadian company has said it believes a merger with Allergan would create an "unrivaled platform for growth and value creation." The company is expanding from generic drugs into areas where it has a smaller presence such as ophthalmology, dermatology and dentistry.
Allergan, based in Irvina, Calif., also has a successful portfolio of ophthalmic drugs to treat conditions such as glaucoma and dry eye, making it an attractive target.
Terms of the deal have yet to be finalized, but Ackman said in the filing that Valeant will pay with a combination of stock and cash and expects the cash component to total around $15 billion.