A task team has raided 13 Auction Alliances properties across the country, the Hawks said on Wednesday.
"We conducted search and seizure operations at five Auction Alliance properties in Gauteng, five in the Western Cape, one in KwaZulu-Natal, one in Eastern Cape and one in the Free State," spokesman McIntosh Polela said.
"The search was to get anything that will help us with the on-going investigation into Auction Alliance."
Auction Alliance made news in December when billionaire Wendy Appelbaum alleged that the firm had used a ghost bidder to push up the price of the wine farm Quoin Rock, which she bought for R55 million on auction.
Investigations were also launched into claims of staff receiving kickbacks for preferential treatment.
Polela said the Hawks, the Treasury, the National Prosecuting Authority, the Special Investigating Unit and the SA Revenue Service formed part of the anti-corruption task team that raided the properties.
"We will only be able to know in a few days what exactly was seized," he said.
In June, the Cape High Court postponed an application by the Estate Agency Affairs Board for a warrant to access Auction Alliance's documents.
Auction Alliance had asked the court to prevent a "warrant-less search" by the board's inspectors.