Real-time bidding (RTB) may be a source of concern and confusion for both media buyers and sellers, but that isn’t stopping adoption of RTBs.

According to a report published this week by sell-side platform Index Platform, the number of RTB impressions sold via its platform jumped nearly 30% in the first and second quarters of the year. What’s more: growth was driven by both major advertisers, which accounted for 57% of all spend in Q2, and local advertisers, which increased their spend by nearly 50% quarter-over-quarter.

All told, Index Platform saw advertisers in 80% of sectors increasing the number impressions bought via RTB, suggesting that, despite real-time bidding’s imperfections, adoption will continue to grow.

The big questions: just how much will it grow, and how rapidly? According to eMarketer, RTB spend in the United States will reach $7.1bn by 2016 — nearly a third of the display ad market — up from $1.9bn this year. Much of the growth will come in the next year, with the RTB train slowing in 2014 and beyond as it becomes an ubiquitous part of the landscape.

Sources of growth

So where will the growth come from? eMarketer believes Facebook’s presence in the RTB space will play a role in propelling 72% year-over-year growth in RTB spend next year. It also sees “an expected influx of video and mobile inventory” and “an anticipated greater availability of premium ad inventory.”

Obviously, the jury is still out on the impact of real-time bidding in the video and mobile markets, and while the numbers make it clear that, despite their skepticism, publishers aren’t shunning RTBs, the growth of premium inventory will depend on a number of factors.

The good news for those betting on RTB: Index Platform says that the average CPM of inventory moved through its platform in the second quarter rose by 7.8%, and numerous segments, including movies and gaming, saw average CPM increase over 10%. And with high-profile publishers like VEVO demonstrating new approaches to taking advantage of real-time bidding, there’s hope that RTB doesn’t have to be a race to the bottom for media sellers.