An investigation into alleged money-laundering prompted police to search an office in Belper.
Police executed warrants at seven properties across Derby, Ashbourne and Belper on Tuesday, October 1.
The operation saw 130 police officers team up with the Serious Organised Crime Agency, HMRC and the Department for Business, Innovation and Skills.
A 53-year-old man and a 43-year-old woman were arrested at a property in Yeaveley, near Ashbourne, on suspicion of offences including money laundering.
A man aged 36 was arrested in Derby, while two women aged 23 and 24 were arrested at another address in Derby, and in Allestree, on suspicion of assisting a disqualified director to break a disqualification order.
Four of those arrested remain in custody, while the 23-year-old woman was released on bail.
No arrests were made during the search of the Belper office. Police said they were not prepared to reveal which building had been searched.
Anyone with information should contact Crimestoppers, anonymously, on 0800 555 111 or Derbyshire police on 101.