Wyeth (WYE) shareholders voted overwhelmingly to sell the drug maker to Pfizer Inc. (PFE) Monday, hitting a key milestone on the way to the mega-merger's expected closing later this year.

Some 98% of Wyeth shares voted were cast in favor of the deal, according to a preliminary tally announced a shareholders' meeting in Morristown, N.J., which was available by Webcast.

The deal is still subject to clearance by antitrust regulators in the U.S. On Friday, Pfizer announced the European Commission had approved the deal, subject to Pfizer's pledge to shed certain animal-health assets in Europe. U.S. regulators also expect animal-health divestitures because Pfizer and Wyeth have overlapping animal-health businesses.

New York-based Pfizer expects the deal to close by the end of the year.

In January, Pfizer agreed to acquire Wyeth, based in Madison, N.J., in a cash-and-stock deal then valued at about $68 billion. Pfizer is striking the deal to help diversify its business and gain access to fast-growing biotechnology-style drugs and vaccines, all to help soften the blow of the impending loss of patent protection for Pfizer's blockbuster cholesterol drug Lipitor in 2011. Also, Pfizer expects significant cost-savings from the deal, with a planned 15% reduction in the combined entity's work force planned.

Wyeth shareholders were sold on the takeover thanks to a nearly 30% premium to Wyeth's share price before news of the merger talks leaked in late January.

Wyeth Chief Executive Bernard Poussot said Monday the combined entity will achieve more than either company could have alone. But he acknowledged "mixed feelings" and "sadness to see the company disappear as we know it today," as well as pending loss of jobs for many Wyeth employees.

Wyeth shares rose 3 cents to $46 Monday. Pfizer was off 2 cents at $14.94. The deal originally valued Wyeth at $50.19 a share.

-Peter Loftus; Dow Jones Newswires; 215-656-8289; peter.loftus@dowjones.com