Pfizer Inc. is on the verge of abandoning, for now, its effort to buy for 69.4 billion pounds ($117 billion) in what would have been the biggest deal ever in the drug industry.

The deadline for Pfizer to make a firm offer arrives Monday, and the New York-based drugmaker almost certainly will announce that it won’t do so, said a person familiar with the plan who asked not to be identified because the process is confidential.

Under U.K. government rules, the two drugmakers face an at least three-month cooling off period before talks can restart, giving both time to figure out their next move. Pfizer is hoping that AstraZeneca investors will use that time to put pressure on the company’s board to come back to the table, the person said, while AstraZeneca may seek a revenue-generating acquisition of its own to help it fend off the larger company. 

“The probability of a future AstraZeneca acquisition is dimmed, but not entirely extinguished,” said Mark Purcell, an analyst with Barclays Plc, in a note to clients.

Pfizer, the biggest U.S. drugmaker, has declined to say if it will try again to buy London-based AstraZeneca after the U.K. company’s board rejected its last offer of 55 pounds a share. For talks to begin anew after three months, AstraZeneca must invite the discussion. Otherwise, Pfizer needs to wait six months to make a new bid.

Pfizer probably will issue the statement this afternoon London time saying it won’t make an offer, the person said. Under U.K. rules, it’s required to put the statement out by 5 p.m.

Esra Erkal-Paler, an AstraZeneca spokeswoman, and Joan Campion, a Pfizer spokeswoman, both declined to comment.

AstraZeneca rose 1.2 percent to close at 43.28 pounds on May 23. Pfizer fell 0.6 percent to $29.49. Stock markets in both the U.S. and the U.K. are closed Monday for holidays.

Both companies set themselves up with massive expectations during a very public debate over the proposed deal. AstraZeneca has predicted sales of $45 billion by 2023, a 75 percent increase from last year. The company has bet heavily on a new class of cancer drugs that use the body’s immune system to attack tumors, experimental drugs Pfizer has said it covets.

Pascal Soriot, AstraZeneca’s chief executive officer, “made a bet on the pipeline and he will be under pressure to deliver on the targets he gave to the market, which are very bullish and, in my opinion, not too realistic,” said Odile Rundquist, a Helvea SA analyst based in Geneva. (Bloomberg)