A Toronto investment firm, victimized by a former employe, suffered added injury as the Investment Dealers Association of Canada (IDA) hit it today with a $250,000 levy for breach of IDA bylaws and inadequate supervision of its Calgary office.

Merrill Lynch Royal Securities Ltd. agreed to pay settlements of $250,000 to the IDA, according to a bulletin sent to IDA members. The firm is the Canadian subsidiary of Merrill Lynch, Pierce, Fenner & Smith Inc., a giant New York-based brokerage firm.

As part of the agreed settlement, the Merrill Lynch unit also agreed to furnish information on its internal control procedures for the next two years.

The penalty is the largest cash levy ever imposed by the IDA on a member firm. The IDA is the Canadian equivalent of the Investment Bankers Association and is the national self-regulating body of the securities industry. Gordon Jones, Merrill Lynch Royal Securities president, is chairman of the IDA.

To date, the investment firm has collected $5 million as part of a settlement of its insurance claim related to trading during 1979 in shares of Brent Petroleum Industries Ltd. of Calgary, Jones said. But he would not comment further on the settlement.

There were numerous irregular transactions in Brent shares through the Calgary office, and a former Merrill employe was convicted of defrauding the public in the Brent trading.

During 1979 Brent stock jumped to $30 a share from $13 in less than three weeks. An investigation by the Royal Canadian Mounted Police found that the former employe defrauded the Merrill Lynch unit through unauthorized purchases of 280,000 shares in client margin accounts.

Most IDA settlements involve a variety of sanctions, including cash penalties, reprimands, suspension or cancellation of membership.