NEW YORK – The head of Banknorth Group Inc. rang the opening bell of the New York Stock Exchange on Monday to signal the bank’s switch to the exchange from the Nasdaq stock market.

William Ryan, chairman, president and chief executive officer of the Portland-based company, rang the bell at the 9:30 a.m. opening.

Banknorth switched to the Big Board because of the financial services company’s strong growth in recent years. The company has banking operations in every New England state except Rhode Island, and has become the 34th-largest commercial banking company in the country.

The New York Stock Exchange has the reputation of listing companies that are generally larger than those on the Nasdaq exchange.

“Banknorth exemplifies the qualities of leadership that define NYSE-listed companies,” said Dick Grasso, chairman and chief executive of the exchange.

With the change, Banknorth’s stock trading symbol changes from BKNG to BNK.

Banknorth is the parent company of Peoples Heritage Bank in Maine, Bank of New Hampshire, Banknorth Massachusetts, Banknorth Vermont, Banknorth Connecticut and Evergreen Bank in upstate New York.