Investments in bank shares hours before the royal commission's final report was released has Labor calling for a serious investigation.
Treasurer Josh Frydenberg guaranteed there would be no leaks between his office getting the report and its release three days later.
But Labor says it looks "fishy" that hundreds of millions of dollars were invested in bank shares on Monday morning before the report's release.
"(There was) very substantial movement in the market and there absolutely should be the fullest investigation by all relevant authorities," shadow treasurer Chris Bowen told reporters in Melbourne on Thursday.
"The whole excuse that the government gave us for not releasing the royal commission report on Friday was that it might move the market - and the market moved on Monday.
"We want to know, was any part of the royal commission's report released, and if so, by whom and to whom?"
Shares in the big four banks dropped at the opening of trading on Monday before rising by between 1.7 and 2.1 per cent during the day.
They dropped back to close at between 1.0 and 1.2 per cent, which experts say is not a notable rise.
All four banks have had bigger gains in a single day at least once this year.
Urban Infrastructure Minister Alan Tudge, who filled in for a sick Prime Minister Scott Morrison at an event in Melbourne, said there had been no leak from the government.
"The treasurer addressed this yesterday and said there was absolutely no briefings of anybody else, he was pretty emphatic about that yesterday," he told reporters.
Labor has asked the Australian Securities Exchange, the Australian Securities and Investments Commission, and the Department of Prime Minister and Cabinet to investigate.
Parliament returns next week and Treasurer Josh Frydenberg recently said he wants to quickly pass amendments to a bill extending civil penalties to superannuation trustees - which Labor supports.
But the bill that needs amending is not listed for debate on a draft program for the three days of Senate sittings next week.
Mr Bowen said some of the royal commission's recommendations needed complex work over time.
"There are others which are frankly no-brainers, which could be legislated next week," he said.
The coalition says it is "taking action" on all 76 recommendations of the royal commission, but it is not implementing all of them exactly as Commissioner Kenneth Hayne proposed.
Mr Bowen said Labor's starting position was that a government would need a "very good reason" to change a recommendation from the royal commission, but the party was working through them.
One of those recommendations is a shift to an up-front payment to mortgage brokers, but the coalition is cautious about it and Mr Bowen also said the commission did not recommend it be done urgently.
Labor wants parliament to sit for an extra two weeks in March to ensure financial laws can be fixed as soon as possible, but Mr Morrison says there is no need for extra sitting days.
