Porter, 57, who lives in Corby in Northamptonshire, was charged with fraud relating to actions between January 2011 and September 2013.
He appeared before Lincoln Crown Court at the end of last month and admitted to fraudulent trading by his company Stuart Porter Ltd, and a further five charges involving cash sums of £83,000.
Judge Simon Hirst adjourned sentencing Porter until September 30.
Previously Porter and co-defendants Maxine Norris, of Netherfield, Nottingham and Sophie Norris, of Hull, were charged with carrying on a business to defraud creditors and conspiring with others to steal. They had denied conspiracy to steal furniture, jewellery, ceramics and antiques.
A fourth defendant, Dale Withers, of Wisbech, had been charged with conspiring with others to steal but failed to appear before the court this month.
When Lincolnshire Police began the investigation into Porter three years ago they made an appeal to other antiques dealers to come forward with any information on his business.
Previously Detective Sergeant Jen Lovatt said: “We have been contacted by hundreds of people who are anxious to know if their property has been recovered. We aim to reunite as many items as we can with rightful owners but plead for patience in the meantime as we carry out the complex enquiry.”
The police cannot comment on the case following the court appearance until sentencing has been made at the end of the month.