SOUTH PORTLAND – Banknorth Group Inc. shareholders voted overwhelmingly Friday to approve a $4 billion deal that gives Toronto Dominion Bank a controlling stake.

Toronto Dominion will own 51 percent of Banknorth when the transaction is completed in early March.

“This is not a home run. This is a grand slam,” said William Ryan, chairman, president and chief executive officer of Banknorth. “There is no downside to this transaction.”

Under terms of the agreement, Banknorth shareholders receive 0.2351 shares of TD Bank stock, $12.24 in cash and 0.49 shares of new Banknorth stock for each share of Banknorth stock they now own.

The transaction, announced in August, will give Toronto-based TD Bank a banking presence in the United States while giving Banknorth the resources to continue its growth strategy of acquiring small community banks.

Ed Clark, TD Bank Financial Group president and chief executive, said the deal would give an immediate boost to his company’s earnings while advancing the company’s strategic plan.

“At the end of the day, there are a limited number of acquisitions we can make in Canada,” Clark said.

Many shareholders voted before the meeting by mail, phone or on the Internet.

Banknorth has $30 billion in assets and nearly 400 branches in New England and upstate New York. TD Bank has assets of nearly $240 billion and more than 1,000 branches across Canada.

After the deal is completed, Banknorth stock would continue to be listed on the New York Stock Exchange. Shares of TD Bank are traded on both the New York Stock Exchange and the Toronto Stock Exchange.

Banknorth’s banking subsidiaries now include Peoples Heritage in Maine, Bank of New Hampshire, Banknorth Massachusetts, Banknorth Vermont, Banknorth Connecticut and Evergreen Bank in upstate New York.

After the merger, all the banks would be renamed TD Banknorth, a process that should be completed by the middle of the year.

Ryan will stay as an executive, and no layoffs are anticipated. “This isn’t like other acquisitions you read about around New England,” he said.

Banknorth stock closed Friday at $36.35, up 9 cents.