The proposed merger of marketing consultancies Ebiquity and Nielsen has sparked concerns from the competition watchdog.
Nielsen and Ebiquity monitor the advertising habits of companies and are the only suppliers of this intelligence across the UK media. Ebiquity announced in February that it wanted to sell its advertising division to Nielsen.
The Competition and Markets Authority (CMA), which scrutinises proposed mergers, said that while the companies faced some competition in the digital advertising space, there was no competition firm in the detailed intelligence field across al UK media channels.
The CMA said the same applied regarding the supply of intelligence on international advertising to UK customers.
It gave the the two intelligence sharers until 20 June to answer the CMA's competition concerns before proceedings with a more in-depth investigation, otherwise known as a phase two probe.
Ebiquity said in a statement: "Ebiquity and Nielsen now have the opportunity to offer remedies to address the CMA's concerns. If appropriate remedies are not offered or agreed, the transaction will be referred for a phase two investigation. Ebiquity and Nielsen continue to believe that the transaction will deliver substantial benefits for all stakeholders."