NEW YORK - Pfizer Inc. will likely slash staff and accelerate merger and licensing deals as the pressure on it to improve its financial performance intensified after the weekend's announcement that the company ended development of a key drug.

Analysts differed on how much they believed Pfizer stock would fall when it opened on Monday. Barbara Ryan, an analyst at Deutsche Bank, said she believed the dividend yield of roughly 4 percent would keep shares from a free fall, but another analyst estimated the stock could plunge to $20 a share. Pfizer shares closed Friday at $27.86 on the New York Stock Exchange.

The world's largest drugmaker said Saturday that an independent board monitoring a study for cholesterol treatment torcetrapib recommended that the work end because of an unexpected number of deaths.

The news is devastating to Pfizer, which had been counting on the drug to revitalize stagnant sales that have been hurt by numerous patent expirations on key products.