NEW YORK — Pfizer Inc.'s decision to scrap development of a crucial medicine sent its shares plummeting yesterday as analysts fretted about its future and speculated about which companies it might purchase to shore up its pipeline.

Shares of Pfizer fell $2.96, or 10.6 percent, to close yesterday at $24.90 on the New York Stock Exchange.

On Saturday, Pfizer said it had halted development of the cholesterol drug torcetrapib because of an unexpected number of deaths and other complications in the trial.

Torcetrapib was supposed to fill the void when Pfizer's best-selling drug, cholesterol treatment Lipitor, loses patent protection, possibly as early as 2010. Other patent expirations will rob Pfizer of $14 billion in revenues annually between 2005 and 2007.

Now the revenue gap is looming larger than ever. Analysts said Pfizer has some interesting products in its pipeline but none that come close to torcetrapib's promise, intensifying the pressure to find new medicines.

One avenue is for Pfizer to buy smaller drug companies to gain the drugs they're developing. Pfizer can fund a substantial shopping spree: It has $13 billion in cash and short-term assets, and will reap $13.5 billion from the sale of its consumer products division to Johnson & Johnson, expected to close by year's end.

As much as analysts believe Pfizer will act swiftly to bring new products into the fold, they caution it is no panacea. This year, Pfizer canceled at least two drug-development deals. Last month, it pulled out of its deal with drugmaker Organon to develop schizophrenia treatment asenapine, and over the summer it returned its development and marketing rights on sleeping pill Indiplon to Neurocrine Biosciences Inc.

Pfizer is in a tough spot because it wants to show investors it is taking actions to improve its fortunes, but purchasing another company or licensing products also is very risky, said Jason Napodano, an analyst at Zacks Independent Research, who downgraded Pfizer stock to "sell" from "hold" yesterday.

Most analysts don't believe Pfizer will acquire a major drugmaker because it would be expensive and difficult to integrate.