Traders from as far away as Australia were bidding into the night to own machinery which belonged to defunct construction firm Patton.
Wilson's Auctions said the resale of machinery and vehicles from Ballymena-based Patton attracted around 700 bidders, including 100 online.
Hundreds flocked to Wilson's Auctions in Mallusk, Co Antrim for yesterday's auction, which began at 11am and continued into last night.
The auction was unreserved with the aim of fetching the maximum possible for the lots, which ranged from heavy plant machinery to 30 company cars, including executive BMWs.
Ricky Wilson of Wilson's Auctions said: "The auction has been excellent and the crowd has been getting busier as the day goes on.
"It's such a positive sign that small and medium-sized businesses from across Northern Ireland are out in force bidding on great quality plant machinery. They are buying them to put them back into use so that they will be on other building sites from tomorrow.
"The quality of the Patton assets is very good because they were so well looked after, so that adds value to the resale of the assets."
He said online bidding was being conducted from around the world, including Egypt, Scandinavia, New Zealand and Australia.
"There is strong demand for that sort of heavy plant equipment from Australia, which has a strong construction industry."
He would not say how much they hoped to raise from the process but the proceeds are expected to be put towards the debts of Patton, which went into administration last month. It's estimated that around 70 sub-contractors of the firm are owed £15m.