Pfizer Inc. (NYSE: PFE) and Allergan Plc (NYSE: AGN) agreed to combine in a record $160 billion deal, creating a drugmaking behemoth called Pfizer plc with products from Viagra to Botox and a low-cost tax base.

Pfizer will exchange 11.3 shares for each Allergan share, valuing the smaller drugmaker at $363.63 a share, according to a statement Monday. That’s a premium of about 27 percent above Allergan’s stock price on Oct. 28, before news of the companies’ discussions became public. Pfizer investors will be able to opt for cash instead of stock in the combined company in exchange for their shares, with as much as $12 billion to be paid out.

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