Revenue for Nielsen in the fourth quarter of 2018 was $1.7bn, down 5.8% on the previous year.

Over the full year, revenues from the company’s Watch segment increased by 2.3%, or 2.2% in constant currency, to $3.4bn, but dropped 3.5% in the final quarter, compared to the fourth quarter of 2017. 

The Buy segment, which provides data on consumers’ purchase behaviour, decreased by 4.1% ( 3.7% in constant currency) over the course of 2018 to $3.1bn. Revenue also fell by 8.4% in the final quarter for this part of the business.

The company has renamed its two businesses as Nielsen Global Media and Nielsen Global Connect. This move, said chief executive David Kenny, will align its “external view” with its “go-forward internal view” and “help drive greater accountability throughout the organisation”, as well as being “consistent with a product-driven focus”.

Nielsen announced a strategic review of its Buy segment after disappointing second-quarter results in 2018, later expanding the review to include the possibility of a sale. Options also include continuing to operate as a public, independent company or a separation of either of its segments.

Kenny said: "The strategic review is ongoing and the board is working with urgency on this process. The process that we are undertaking will enable us to determine the best path forward in order to maximise value for all of our shareholders."

He added: "2018 was a challenging year but we delivered on our key operational metrics for the second half and positioned ourselves for 2019. Our focus for 2019 is on transforming into a truly product-driven, technology organisation, able to make faster, bolder decisions. We expect these strategies to translate into improved performance in 2019 and beyond as we increase our value to clients."