NEW YORK: AT&T, American Express and Verizon are among the companies making the greatest use of real-time bidding (RTB) to buy online display ads, research from The Rubicon Project has stated.

The advertising technology group drew on data from 6bn daily impressions and 350bn bids on its REVV platform, to assess RTB activity. RTB systems allow brands to compete in automated auctions to serve ads to individual users in real time, allowing in theory for much more precise targeting and efficient inventory pricing.

AT&T, the telecoms specialist, led the global charts, despite having reduced its expenditure by 30% when compared with October. Zalando, the German ecommerce firm, claimed second place, up by 11%.

"The world's biggest brands are using automated ad purchasing to more efficiently reach their target audiences across the world's most premium web publishers," said Frank Addante, chief executive and founder of the Rubicon Project.

American Express, the financial services provider, took third spot but cut its monthly outlay by 23%. Verizon, the communications conglomerate, was fourth, having raised its expenditure by 13%.

Chrysler, the automaker, registered a modest 1% lift in October, while Southwest Airlines, the air carrier, recorded a 64% improvement on the same metric.

Dell, the information technology giant, boosted its budget by 50%. Less positively, Toyota, another car manufacturer, was down by 7% and Unilever delivered a 45% contraction versus October.

General Motors, also from the automotive category, logged the most sizeable expansion, of 110%, among the top ten players.

Looking at the US, where the market is expected to attain an annual value of $7bn according to Addante, AT&T, Verizon, Southwest Airlines, Chrysler and Unilever completed the top five.

Elsewhere, the study revealed that Talk Talk, the telecoms retailer, led the UK charts in November, and was up by 3%, Tesco, the supermarket chain, claimed second after a 58% lift.

BSkyB, the broadcaster, posted a 24% drop, while American Express raised its UK spending by 52% and BT, the communications firm, supplied a 73% increase.

Addante told AdWeek that brands in the UK were embracing real-time bidding "far faster than the US", and were also "leading on the use of technology and ... thought leadership". 

Data sourced from The Rubicon Project/AdWeek; additional content by Warc staff