Suffolk Bancorp shareholders have approved the company’s proposed merger with Connecticut-based People’s United Bank, according to a Suffolk Bancorp statement.

More than 97 percent of Suffolk shareholders approved the proposed sale of the financial institution, the bank said in a release on Thursday afternoon.

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The all-stock deal, which was announced in June, is worth about $402 million. The merger still needs regulatory approval.

Suffolk Bancorp is the Riverhead-based holding company for Suffolk County National Bank, which has 27 branches.

People’s United Bank of Bridgeport, Connecticut already has a presence on Long Island. The bank purchased 56 branches from Citizens Financial Group in 2012, including 52 New York-based Stop & Shop locations.

People’s United also bought Bank of Smithtown in 2010. It has nearly 400 branches in Connecticut, New York, Massachusetts, Maine, New Hampshire and Vermont.