Before it completes its $68 billion acquisition of Wyeth by the end of this year, Pfizer Inc. also is expected to sign a $2.3 billion settlement with the federal government over charges that it illegally promoted several of its drugs.

The settlement would be the largest ever paid by a drug company for such activity.

Because Pfizer, based in New York, had said in January that it was setting aside $2.3 billion to cover the expected settlement, investors were not expecting the announcement of a final deal to affect the company's stock value.

"I think the Street tends to look at these big settlements as the cost of doing business," said Les Funtleyder, who follows pharmaceutical companies for Miller Tabak & Co. L.L.C.

Pfizer, which would not comment yesterday on how soon it would announce details of the settlement with the U.S. Attorney's Office in Massachusetts, previously had said that federal investigators were focusing on several products, including its painkiller Bextra. Pfizer has taken Bextra off the market.

The U.S. Food and Drug Administration had approved Bextra to treat arthritis pain. Federal investigators are looking into whether Pfizer employees promoted the drug for other types of pain, such as the pain of surgery.

Drug companies can market their products only for FDA-approved uses, but doctors can prescribe as they see fit.

No one from the U.S. Attorney's Office in Massachusetts returned a call for comment.

Wyeth, based in Madison, N.J., has large operations in Collegeville. The Pfizer-Wyeth deal was announced in January. Pennsylvania officials have discussed possible incentives to keep about 5,000 Wyeth jobs in the Philadelphia region.

Pfizer shares closed yesterday at $16.38, down 32 cents, or 1.92 percent. Company shares have traded in a 52-week range of $11.62 to $19.59.

Wyeth shares closed at $47.79, down 6 cents. They have traded in a 52-week range of $28.06 to $48.30.

Contact staff writer Miriam Hill at 215-854-5520 or hillmb@phillynews.com.