NEW YORK: Three of America's five biggest TV networks registered a decline in ad revenues last year according to figures from TNS Media Intelligence, with only Fox and NBC posting overall increases, which were partly attributed to their respective broadcasts of the Super Bowl and Olympics.

Alan Wurtzel, president of NBCU Research, has argued that the Olympics acted as a “billion dollar research lab” for the company, providing an insight into viewer behaviour across a number of different mediums, including TV, mobile and online.

The company saw its total ad sales rise by some 8.3% last year to $5.39 billion (€4.1bn; £3.7bn) from $4.98bn in 2007, though this figure was down from slightly over $6bn in 2006.

Fox, which is owned by News Corp, posted an increase in adspend of 5.4% to $4.59bn, up from $4.35bn on an annual basis.

By contrast, spending through CBS dropped off by 6.7% last year to $6.64bn, compared with $7.12bn in the previous 12 months, with revenues said to have been impacted by the writers' strike and the loss of rights to show the Super Bowl.

ABC, part of The Walt Disney Company, also posted a decline of 0.8% to $6.16bn from $6.21bn, but this figure was still improved from $5.90bn in 2005.

Finally, The CW, a joint venture between Time Warner and CBS, registered a slide in advertising expenditure of 13.1% to $790m, from $909m in 2007.

Data sourced from; additional content by WARC staff