TD Bank Financial Group is buying shares of TD Banknorth on the open market to maintain or possibly increase its majority stake in the American bank.

TD, which competed its $5 billion acquisition of 51% of Banknorth shares last March, said today it will maintain its ownership at the same level as before TD Banknorth took over Hudson United Bancorp.

That acquisition, valued at about US$1.9 billion, was completed Tuesday.

TD said preliminary figures show that of the 45 million shares of Hudson United common stock, holders of 18.6 million elected to receive US$42.42 per share in cash, while 18.1 million exchanged each share for 1.4 Banknorth shares and 8.3 million did not make a valid election and were deemed to have chosen shares.

This indicates TD Banknorth will be issuing about 37 million shares to Hudson United investors in the acquisition, which extends TD Banknorth’s growth in Connecticut, eastern New York, New Jersey and Philadelphia.