During the second quarter of the year, the highest-risk inventory was served via ad exchanges. That's according to a report to be released Wednesday by AdSafe Media, a company that markets proof-of-performance and content safety solutions.
A full 16.9% of inventory served by ad exchanges was high risk for advertising, while 6.3% of inventory served via ad networks was high risk, and 3.8% directly via publishers was considered high-risk.
What's more, inventory transparency is the lowest on ad exchanges, which served 64.4% IAB Category I inventory -- with full transparency regarding referring URL -- while ad networks served 82.6%, and publishers directly served 97.4%.
Publishers, the study found, tend to follow geotargeting requirements more than any other buying channel. The study revealed that 1.9% of publisher inventory fell outside of geotargeting requirements, while 3.9% of ad exchange inventory and 4.3% of ad network inventory fell outside of geotargeting requirements.
During the second quarter of the year, nearly half -- 49% -- of traffic was served via ad exchanges, real-time-bidding platforms, and demand-side platforms -- an upward trend from last quarter's 47% share. Meanwhile, 33% of traffic was served via ad networks, and 18% was served directly via publishers, according to the report.
The slight uptick reflects the industry's continuing shift toward the buying of "audiences" versus "sites," according to AdSafe Media.
As advertisers and agencies continue to adopt the use of these buying channels as a means to increase the efficiency of media spend, it expects to see the share of traffic flowing through non-direct channels increase in the third quarter and beyond.
Yet inventory transparency continues to be a significant issue with traffic served from ad exchanges due to a number of contributing factors, primarily the re-brokering of inventory and the use of iFrames.
"Daisy chaining," or the re-brokering of inventory between sales platforms, is often a necessary practice for ad exchanges to provide adequate liquidity of inventory, according to AdSafe.
However, concerns over the lack of information regarding the exact page-level location of the URL are limiting some agencies and advertisers from buying through ad exchanges.
Also, as ad exchanges continue to aggregate inventory from "long tail" publishers like blogs, social media and other non-premium publishers, AdSafe expects to see an increase in the prevalence of inventory that is high risk for advertisers.
A key reason that display continues to lag behind paid-search advertising is that major marketers are concerned by the increasing lack of "transparency" among ad networks and third-party aggregators of online display advertising. That's according to a report released in April by the Winterberry Group and commissioned by AdSafe.
The study found that some of the key issues related to display ad transparency include "message misalignment" (advertising message appears out of context from surrounding Web page content) and outright "dangerous" placements (ads appearing on pages that defy good "taste, respect and basic courtesy").