The activist hedge fund management firm said in a regulatory filing on Monday ( 13 August) that it has accumulated a share of Nielsen, and will "encourage the issuer to undertake a full strategic review of, and initiate a process to explore, the sale".

According to a report in the Wall Street Journal (WSJ), the company plans to urge Nielsen to sell. 

Reports of Elliott’s investment led to Nielsen’s stock price increasing by over nine per cent, after previously tumbling by up to 27% following disappointing second quarter results.

The WSJ reported that Elliott Management believes Nielsen’s Buy segment, which tracks consumer purchases, has not kept up with competitors.

Last month, the company launched a strategic review of the segment, with second quarter revenues decreasing 4.1% to $789m or 5.4% year-on-year on a constant currency basis.

Nielsen’s chief executive Mitch Barns (pictured) is to retire at the end of the year, with James Attwood, the current chairman of the board and managing director at The Carlyle Group, becoming executive chairman in charge of the search for a new CEO.

A company spokesperson for Nielsen said: "On July 26, 2018, the board announced that it is conducting an in-depth strategic review of Nielsen’s Buy segment in order to identify the most appropriate options for this segment going forward. The board continues to evaluate opportunities to best position the business for long-term success and growth and to generate value for all shareholders. 

"The board and management regularly engage with shareholders and welcome the views and perspectives of its owners, including Elliott. Nielsen remains focused on its mission of providing clients with the most complete understanding of what consumers watch and buy with world-class measurement as well as analytics."