SYDNEY (Reuters) -Australia's Macquarie Group ( MCQEF ), will repay A$321 million ($211.35 million) to thousands of customers who invested their retirement savings into the now-collapsed Shield Master Fund, the country's corporate regulator said on Thursday.

The Australian Securities and Investments Commission (ASIC) has launched Federal Court proceedings against Macquarie Investment Management after it failed to act "efficiently, honestly and fairly" by not placing Shield under heightened monitoring.

The unit oversaw A$321 million ($211.35 million) in pension investments into Shield by nearly 3,000 people through Macquarie between 2022 and 2023, the regulator said.

"Many members thought their funds were safe when they used Macquarie's super platform to invest in Shield, which had no track record," ASIC deputy chair Sarah Court said in a statement.

The ASIC action is the second major run in between Macquarie and the corporate regulator since May.

ASIC began legal action against the bank alleging it misreported up to 1.5 billion short sales over the past 15 years - marking the fourth action against Macquarie in the past year.

The Shield fund was offered on a Macquarie platform which has hundreds of investment options which can be accessed through a financial advisor.

Macquarie, in a separate statement, said it would repay by Tuesday the full amount lost in Shield's collapse.

Macquarie will then attempt to recoup some of the funds lost by its investors through the Shield liquidation process that is being led by Alvarez & Marsal.

Macquarie said the process of recovering the funds could take many years.

The Shield Master Fund was put into liquidation in 2024 and is being investigated by ASIC for mishandling retirees money.

ASIC said it would not seek penalties given Macquarie's cooperation and the 'strong public interest' in securing timely court-based resolution.

It said Macquarie had agreed to enhance investment governance processes on its wrap platform under a plan agreed with the Australian Prudential Regulation Authority.

($1 = 1.5188 Australian dollars)