The Federal Court has ordered Commonwealth Securities to pay a fine of A$20 million and Australian Investment Exchange Ltd (AUSIEX) to pay a fine of $7.1 million for breaches of the Market Integrity Rules, Corporations Act and ASIC Act.

The penalty is the largest ever handed down for breaches of the Market Integrity Rules.

The court said the breaches represented “systemic compliance failures”, including overcharging CommSec customers for brokerage fees on more than 120,000 occasions.

CommSec is a wholly owned subsidiary of Commonwealth Bank and AUSIEX was a CBA subsidiary at the time the breaches occurred. AUSIEX has since been sold to Nomura Research Institute.

The court also ordered an independent review of all systems and controls relating to the provision of financial services by the two companies, along with a review of their remediation.

Among the breaches found by the court, the companies failed to comply with their client money reconciliation requirements, did not provide accurate confirmations to customers of certain market transactions and failed to comply with their “best execution” policies and procedures.

The court also declared that CommSec and AUSIEX failed to do all things necessary to ensure their financial services were provided efficiently, honestly and fairly.

CBA issued a statement saying CommSec co-operated with ASIC in relation to its investigation and the court accepted that there was no evidence to indicate any of the contraventions were deliberate.

ASIC said in a statement that CommSec has been before the Market Disciplinary Panel for contraventions of the Market Integrity Rules on seven previous occasions since 2012 and been fined $1.05 million.

It was the subject of a court enforceable undertaking in 2013 for client money and trust account failings.