Pharmaceutical company Actavis Plc announced Monday it has entered into a definitive agreement to acquire Botox maker Allergan Inc. for $66 billion, which will create one of the top 10 global pharmaceutical companies by sales revenue. Following the news, shares of Allergan (NYSE:AGN) jumped more than 7.45 percent to $213.44 in morning trading on the New York Stock Exchange. 

The deal will prevent a hostile takeover by Valeant Pharmaceuticals and Bill Ackman's hedge fund, Pershing Square Capital Management.

Actavis, a private Irish pharmaceutical firm, said the transaction is valued at $66 billion, or $219 per share, in cash and Actavis shares based on the closing price of Actavis shares on Nov. 14. Actavis will acquire Allergan for a combination of $129.22 in cash and 0.3683 Actavis shares for each share of Allergan common stock. 

Representatives from Actavis and Allergan did not immediately respond to request for comment.

"This acquisition creates the fastest growing and most dynamic growth pharmaceutical company in global health care, making us one of the world's top 10 pharmaceutical companies," Brent Saunders, CEO and president of Actavis, said in a statement.

The combination is projected to create synergies of at least $1.8 billion with combined annual pro forma revenues (revenues used to forecast future growth) of more than $23 billion anticipated in 2015, Actavis said. 

“We are combining with a partner that is ideally suited to realize the full potential inherent in our franchise,” said David Pyott, chairman and CEO of Allergan.

The transaction has been unanimously approved by the boards of directors of both Actavis and Allergan. The deal is subject to regulatory approvals and Actavis anticipates the transaction will be completed during the second quarter of 2015.