NIQ (also known as NielsenIQ, formerly known as ACNielsen or AC Nielsen) is a global marketing research firm, with worldwide headquarters in Chicago, United States.

Nielsen Holdings divested its consumer intelligence (by then known as NielsenIQ) business to private equity firm Advent International.

In 1950, A.C. Nielsen acquired the C. E. Hooper company and began attaching recording devices to a statistical sample of about 1200 consumer television sets in the United States.

[8] The company began expanding internationally in 1939, their first location outside of the USA was in the United Kingdom in the city of Oxford, of which today still remains NIQ's UK HQ.

Panel members carry an electronic monitor that detects the digital station and program identification codes hidden within the TV and radio broadcasts they are exposed to.

[12] On January 22, 2015, Nielsen acquired Brandbank, specialized in the process of digitally collecting, managing and distributing FMCG product and brand image content for retail syndication across in-store, print promotional and e-commerce platforms.

This approval was given under the condition of selling GfK consumer panel business, which went to the British market research company YouGov in July 2023.