Myth #2: Vertical networks are too small/niche/expensive to be effective.
Reality: Vertical ad networks that focus on a single industry can build significant scale for advertisers seeking a highly desirable, very specific target audience. Particularly for verticals that have a somewhat complicated supply chain, regulatory environment or multiple stakeholders (such as automotive or travel), a vertical network can offer greater marketing expertise and intelligence in its category than a full-service ad network may be able to provide. Vertical networks can offer not just reach and industry knowledge to potential advertisers but also greater transparency than some of the larger, horizontal networks.

Myth #3: Ad networks offer efficient reach vehicles.
Reality: Another effect of consolidation in the ad network industry is the increase in reach, with the largest, Platform A, claiming over 90 percent reach to U.S. internet users. However, there is a marked difference between the reach reported by the measurement companies and what is available to advertisers.

There needs to be a more nuanced understanding of reach online. The networks tend to experience a power law distribution, where a small minority of their audience also has a high number of page views per user, and the vast majority of users might be "touched" by the network once or twice per month. While in theory, the networks present a great opportunity for branding, marketers must also consider if their effective frequency will equal or exceed their planned frequency. If the majority of users in the network see an ad once but then don't see it again for another 24 days, how effective will that ad be?

The good news is that the larger networks have a strong sense of where their audience is online, and they are likely to fulfill the terms of a buy with higher planned frequencies. These days, a smart advertiser can find efficiency and effectiveness everywhere, but they can't find scale everywhere. The networks are still one of the most scalable advertising opportunities available.