Online stockbroker CommSec has admitted to overcharging customers and other breaches, and it could face a penalty on top of $6.5 million it has refunded.

The corporate regulator said CommSec overcharged customers on 120,933 occasions, more than $4.35 million in brokerage fees between August 2010 and February last year.

ASIC has commenced court proceedings against CommSec and Australian Investment Exchange Limited (AUSIEX), the broker's wholesale arm, which the Commonwealth Bank agreed to sell last year.

CommSec and AUSIEX have also admitted to a slew of "systemic compliance failures", including not providing accurate confirmation to customers for certain transactions and failing to comply with best execution policies.

Share trading platforms including CommSec have seen an influx of new customers over the past year, as record low returns on savings accounts and the booming stock market have spurred retail investors to enter the market.

Last month, CBA said more than 230,000 new CommSec accounts were opened between June and the end of December last year, with the value of trades through the platform doubling from a year earlier.

In a statement on Monday, CBA apologised to customers and described the failures as mistakes caused by coding and system errors, human error and data entry errors.

It said CommSec had repaid a total of $6.5 million to customers, including refunds, compensation and interest payments.

"We acknowledge the importance of meeting our compliance obligations and we are committed to continuing to invest in strengthening our systems and procedures," CommSec managing director Richard Burns said.

RBA surprises with $4b bond purchase

The Australian share market has risen and the Reserve Bank is buying $4 billion of longer-dated government bonds as it battles to keep interest rates near its record-low target.

The ASX 200 gained 1.7 per cent to 6,789 points, while the All Ordinaries index rose 1.5 per cent, recovering some of the sharp losses posted at the end of last week.

The top-performing stocks on the benchmark index were Austal (+8.4pc), Reece (+7pc) and Clinuvel Pharmaceuticals (+6.5pc).

Real estate companies rose following news house prices continued to climb last month, with shares in Charter Hall (+5.6pc) and Stockland (+5.5pc) up strongly.

Gold mining stocks were among the worst performers on the market, with falls for Ramelius Resources (-3.5pc) and Silver Lake Resources (-3.5pc).

Shares in Fortescue fell 5.9 per cent as it traded "ex-dividend", meaning shares bought from Monday are not entitled to the miner's next dividend payment.

The Australian dollar was up by about half a per cent against the greenback, buying 77.48 US cents at 4:20pm AEDT.

Ahead of its board meeting tomorrow, the Reserve Bank said it would purchase $4 billion worth of Australian government bonds, due to mature between November 2024 and May 2028.

That is double the typical size of the RBA's purchases under its quantitative easing program, which was extended to $200 billion last month.

The offer for the longer-dated bonds followed an unscheduled purchase of $3 billion of three-year bonds by the RBA on Friday, as the rout on global bond markets sent yields further above its 0.1 per cent target.

Bond yields have soared in recent weeks with investors betting inflation will rise as global economies recover from the pandemic and force central banks to raise interest rates sooner than expected.

However, some calm has returned, with the yields on US 10-year treasury notes coming off their peak at the end of last week. The Australian 10-year yield, meanwhile, slid on Monday.

"The bond moves on Friday still feel like a pause for air, rather than the catalyst for a move towards calmer waters," NAB strategist Rodrigo Catril said.

"Market participants remain nervous over the prospect of higher inflation as economies look to reopen aided by vaccine roll outs, high levels of savings along with solid fiscal and monetary support."

Betashares chief economist David Bassanese said there was a risk of a correction on equity markets if the bond sell-off did continue.

"The big near-term risk, at least, is a short-run spike in inflation which could lead to a further capitulation among bond investors and pull back in equity markets," he said.

Crown admits to underpaying workers

Shares in Crown Resorts rose 1.5 per cent despite news the casino operator was facing another investigation, this time by the Fair Work Ombudsman (FWO).

The FWO said Crown had reported itself to the workplace regulator for underpaying staff and that it was now conducting an investigation.

"We expect any employers that identify non-compliance to report to the FWO and fully cooperate with our investigation to ensure that employees are quickly repaid any outstanding entitlements," an FWO spokesperson said.

"Any workers with concerns about their pay should contact us directly for assistance."

In a statement, Crown said it discovered the underpayments in an assessment of its workforce, following media reporting of widespread underpayment issues, particularly in hospitality.

"Our expectation is that only a small proportion of our employees are potentially impacted and that the majority of employees impacted are not covered by an enterprise agreement," a spokeswoman said.

"Crown self-reported this review and continues to cooperate with the Fair Work Ombudsman."

Crown has also announced another resignation, with WA-based director John Poynton stepping down as part of the fallout from the scathing report of the inquiry commissioned by the NSW Independent Liquor and Gaming Authority (ILGA).

Mr Poynton has also left his role as chairman and director of Crown Perth.

Helen Coonan, who is currently acting as Crown's executive chairman following the resignation of chief executive Ken Barton, said the ILGA considered it appropriate for Mr Poynton to step down "due to a perceived lack of independence arising out of his past relationship" with James Packer and the Packer family company Consolidated Press Holdings.

"As a result, John has agreed to resign in the best interests of Crown and our shareholders, despite no adverse findings by the commissioner in the ILGA inquiry in relation to his suitability, integrity or performance," Ms Coonan said.

ANZ to take hit on Malaysian stake

ANZ expects to take a $212 million hit in its first-half results due to its investment in Malaysia's AMMB Holdings Berhad.

AmBank will pay the Malaysian government $US700 million to settle claims in relation to its role in a massive financial scandal, in which $US4.5 billion was allegedly stolen from 1Malaysia Development Berhad, a state fund set up by former prime minister Najib Razak.

Najib was found guilty of corruption and money laundering last year over the transfer of millions of dollars linked to a 1MDB unit into his AmBank accounts between 2014 and 2015.

He has denied any wrongdoing and has filed an appeal.

ANZ owns a 24 per cent stake in AmBank and it said the impact would reduce the carrying value of its interest in the Malaysian company from $1.05 billion to $850 million.

ABC/Reuters