Pfizer has again raised its offer for AstraZeneca, making what it said was a final effort to bring the giant British drug maker to the negotiating table.
The latest offer, made Sunday evening, is worth about $119 billion. It comes after AstraZeneca’s rejection of several private and public offers from Pfizer.
If AstraZeneca rebuffs Pfizer’s offer again, the American company may abandon its pursuit of a merger. Pfizer has said it would not make a hostile offer for AstraZeneca, and would pursue only a friendly deal.
The new offer represents a 45 percent premium over AstraZeneca’s share price before news of Pfizer’s interest became public. Under British takeover laws, Pfizer has until May 26 to make a formal offer. Otherwise it must walk away.
The ball is now in AstraZeneca’s court. A rejection of the offer — and the threat that Pfizer would abandon its effort — could cause the British company’s stock price to tumble.
AstraZeneca did not respond to the latest offer on Sunday night.
The push for what would be the pharmaceutical industry’s biggest deal in more than a decade has set off debates on both side of the Atlantic.
In the United States, where Pfizer has long been a stalwart of American innovation and success, the discussion has centered on the company’s effort to use the deal as a means to reincorporate overseas.
By acquiring AstraZeneca, Pfizer would be able to conduct a so-called inversion, redomiciling in Britain, where it would pay a lower tax rate, potentially saving $1 billion or more a year.
Pfizer is the largest and best-known company to try such a move, and lawmakers in Washington have responded by preparing legislation that would curtail inversions. Senator Carl Levin, Democrat of Michigan, was expected to introduce his bill this week.
In Britain, AstraZeneca has figured strongly in the political debate, as lawmakers from all the major parties, facing a national election next year, express concerns about the potential loss of jobs in the event of a Pfizer takeover.
Indeed, even though AstraZeneca has not agreed to a deal, Pfizer’s chief executive, Ian C. Read, has nonetheless appeared before parliamentary committees to defend his company’s pursuit.
AstraZeneca employs about 6,700 people in Britain, a fraction of its total 51,500 employees worldwide. Nonetheless, British lawmakers are concerned because Pfizer closed a plant in Sandwich, England, in 2011, leading to the loss of 1,500 jobs. Pfizer has committed to keeping open an AstraZeneca research center being built in Cambridge, England.
“We stand by our unprecedented commitments to the U.K. government,” Mr. Read said in a statement on Sunday.
Coming in about 15 percent above Pfizer’s previous offer, the latest proposal would give AstraZeneca shareholders 1.747 shares of the combined company, and 24.76 pounds in cash for each of their shares. That would value each share of AstraZeneca at about £55, or about $92.50.
Still, Pfizer expressed skepticism that AstraZeneca was prepared to agree to a deal.
“We have tried repeatedly to engage in a constructive process with AstraZeneca to explore a combination of our two companies,” Mr. Read said. “Following a conversation with AstraZeneca earlier today, we do not believe that the AstraZeneca board is currently prepared to recommend a deal at a reasonable price.”
Pfizer said it approached AstraZeneca on Friday with a slightly lower offer than the one announced on Sunday. But AstraZeneca said that offer, worth about £53.50 a share, “substantially undervalued” the company, according to Pfizer’s statement.
In response, Pfizer made what it said was its final offer on Sunday. Under the offer, Pfizer shareholders would own 74 percent of the combined company, with AstraZeneca shareholders owning 26 percent.
A sweetened offer had been expected. After being turned down for a second time publicly, Pfizer last week said it would consider making a higher offer, and encouraged AstraZeneca’s board to engage in deal talks.
Pfizer began approaching AstraZeneca earlier in the year, but was told that the company was not interested in a deal. Last month, Pfizer went public with an offer for about $99 billion, mostly in stock. This month, it raised its bid to about $106 billion. AstraZeneca has turned down all offers, saying they undervalue the company.
Mr. Read has continued to press his case. In a recent series of videos outlining his argument for a merger, he said AstraZeneca investors would be wise to accept an offer.
It allows AstraZeneca shareholders to “get an immediate benefit from the cash that we would pay them, it allows them to participate in a very strong combined company with great cash flows and great portfolio, and it allows a very efficient allocation of capital by my company,” he said.
Both Pfizer and AstraZeneca face challenges. Pfizer, the maker of drugs like Viagra and Lipitor, is facing declining revenue and profit as some of its most popular drugs lose patent protection.
AstraZeneca, while it has a promising pipeline of cancer drugs, is also facing struggles with patent expirations and slowing revenue.
Should Pfizer succeed in acquiring AstraZeneca, it would be the capstone to a recent flurry of mergers and acquisitions among drug makers.
“We remain ready to engage in a meaningful dialogue,” Mr. Read said, “but time for constructive engagement is running out.”