GARDINER — Maine securities regulators say Merrill Lynch will pay the state $400,000 to resolve claims that the brokerage allowed some of its associates to sell securities without being properly registered.

Merrill Lynch, Pierce, Fenner & Smith Inc. is a unit of Bank of America Corporation.

A national investigation beginning in 2008 concluded that Merrill Lynch failed to adequately supervise its client associates, who act as sales assistants and administrative support personnel for Merrill Lynch’s financial advisers.

The investigation found that Merrill Lynch’s supervisory system was not reasonably designed to ensure that its client associates complied with registration requirements.

Nationally, the company will be paying $26.5 million in agreements to settle unregistered selling claims.