Oppenheimer and Co. has agreed to pay a $125,000 fine and $30,000 in investigative costs for selling four different unregistered penny stocks through its Portsmouth office, the New Hampshire Bureau of Securities Regulation said Wednesday.

“We determined in our investigation there was a compliance failure,” Jeff Spill, deputy director at the bureau, said. “They were selling stocks that were unregistered.”

Oppenheimer and Co. did not immediately respond to a request for comment.

Under a Consent Order, Oppenheimer also agreed to make whole at least 17 investors, including eight New Hampshire residents, in on one of those penny stocks, Miller Petroleum.

The other stocks identified by Securities Bureau senior auditor William Masuck were Aviza Technology Inc., American International Petroleum Corp. and Tasty Fries Inc.

Besides selling the stocks to clients, Oppenheimer brokers also purchased them for their own accounts, the bureau said.

So-called penny stocks, with a market price of $5 or less, are risky investments that are sold over the counter and not on major stock exchanges, regulators said.

Under the settlement, Oppenheimer’s former Portsmouth office head Jane Dooda is barred for one year from acting as supervisor and branch manager.

Oppenheimer also agreed to retain independent consultant Susan Bryant to review a random sampling of the investment firm’s transactions since Jan. 1, 2004, for evidence of any other sales of unregistered stocks and report in writing within 120 days.

“Securities firms really need to be watching the sale of risky investments like penny stocks,” Eric Forcier, securities bureau staff attorney, said in a statement. “The bureau will hold firms responsible when they fail to properly supervise their brokers.”

The bureau said its investigation showed Oppenheimer sold the penny stocks to two clients who told the firm they were conservative investors.

Oppenheimer will pay back investors’ principal, plus interest, in penny stocks they still hold.

If investors have already sold the penny stocks, Oppenheimer will cover their losses plus interest.

Oppenheimer’s Portsmouth office is at 30 Penhallow St.