The rules, which applied to auctions held in Victoria from Friday, make it mandatory for reserve prices to be published a week ahead of auction dates in an effort to tackle underquoting.
Melbourne led a national drop in the number of homes going under the hammer throughout the week, data from financial services firm Cotality revealed on Sunday.
It follows a broader national trend with the 1423 capital city homes auctioned during the week, down 18.6 per cent from the previous week and almost 46 per cent lower than the same time in 2025.
Melbourne experienced the biggest reduction, with 500 homes hitting auction, down 29 per cent on the previous week and 56 per cent lower than the same week a year earlier.
Cotality research director Tim Lawless said the steep national decline in auctions was driven by a "sharp reduction" in sales under the hammer in the Victorian capital, coinciding with the introduction of the price-disclosure rules.
Clearance rates across the capital cities were the highest in four weeks at 51 per cent, based on preliminarily available data.
Melbourne had the highest preliminary clearance rate at 56.2 per cent, while Sydney, which had the most homes go to auction, had a rate of 54.6 per cent.
Auction clearance rates are considered a strong leading indicator for future price movements with any result below 60 per cent pointing to a falling market.
National house prices have declined 5.2 per cent since March, according to Cotality.
Auction activity was set to further ease heading in the coming week, when 1240 homes were scheduled to go under the hammer, the research firm said.
Melbourne volumes were particularly low, with 489 homes scheduled for auction, 70 per cent fewer than the same time in 2025.
Ray White's chief executive of performance and value Thomas McGlynn said buyer confidence and activity could vary considerably from city to city.
"What's encouraging is that buyers are continuing to engage with the market, although we're seeing them become more considered in their decisions," he said.
"For sellers, there are still opportunities to achieve good outcomes, but understanding local conditions, setting realistic expectations and having the right strategy from the outset are more important than ever."