Rubicon announced this week that it now supports RTB on its platform. This adds to a number of adtech vendors offering this functionality to European ad traders. It is still a nascent buying methodology, but the industry expects the volumes traded through RTB to grow significantly over the coming twelve months. There is no definitive guide to European RTB as of yet. This post will attempt to put together a (very) rough guide to real-time bidding market in Europe: the definitions, the vendors, the technology and the traders.

What platforms are offering RTB functionality for European publishers and media buyers?

- Admeld: One of the first platforms to offer RTB in the European. Unclear what inventory is available through RTB. Admeld have some interesting inventory in UK and mainland Europe.

- Improve Digital: Powered by Pubmatic, Improve Digital is offering some premium inventory through RTB. Particularly strong in markets like France. If you're a French trader and RTB enabled, I'd be talking to Improve.

- Rubicon: Long time sceptics of RTB, announced this week they are entering the real-time trading market. Again it's unclear what inventory will be available.

- DoubleClick Exchange: Adx is RTB enabled, and has inventory available. But again it is in a similar situation to other platforms: the volumes available are limited. This causes an issue with liquidity, and CPM prices are low.

- Orange Ad Market: Possibly the most interesting entry into this market. Not known what inventory will be available through RTB. The platform that underpins the Orange Ad Market, OpenX, already allows RTB on its platform. The possible impressions to buy includes publishers working with Orange network (including Unanimis) and operated and owned properties

- Admeta: A strong European player in the private exchange market. Has RTB functionality but has seen little demand from the market so far.

Those selling European IPs on US inventory:

- AdNexus
- Adbrite

Inventory on these exchanges are unknown but given the RTB volumes in the US there are European IP buying opportunities.

Where is the evidence this actually works - namely the case studies?

There are still very few case studies available on RTB, given that it's early days in this type of media buying. A few of the ad-tech vendors offering RTB have released some case studies on anonymous publishers seeing a lift in CPMs - nothing particularly substantial though. The most interesting case study I've seen is Ebay's recent presentation at the Admeld RTB event. The report highlights the success of Ebay's recent display campaigns bought through RTB. In the video below Daphne Liska explains how the company leveraged vast amounts of data using Appnexus technology to deliver better ROI. There is also some interesting references to high CPMs paid for publisher inventory during the presentation - although no verticals or publishers were mentioned specifically.

How does it all it work together?

Real-time bidding is an easy concept to get your head around, but the technical particulars of the real-time trade are a little more complex. The following articles are essential reading to get a better understanding of how impressions are bought and sold in real time.

Mike Nolet is the CTO at AppNexus and he has written some excellent posts on real time bidding, providing the technical detail that is often missing from marketing puff pieces. Here's three of the best:

- RTB Part I: What is it?
- RTB Part I Followup
- RTB Part II: Supply supply supply!
- RTB Part III — Cookies & User Data

Pubmatic, who offer RTB functionality for publishers and traders, recently produced an excellent whitepaper on real-time bidding. The paper seeks to demystify the technology, the acronyms and the key players in the space. It also advises publishers on who they can partner with on the buy-side. Note that it is a very US-centric report but the same principles can be applied to buying inventory here.

Is this is a lot of marketing BS?

It's easy to be cynical about RTB given all the slick and cynical marketing in ad-tech. Vapourware is everywhere. RTB has a long way to go before it hits its stride. The big problem at the minute is the lack of inventory available here in Europe. This is resulting in very low CPMs but then the inventory available is pretty poor. My advice to publisher is to work with a vendor on the list above, set reasonable floor prices and start trading. The only way to know if it's works is through continuous testing. Take the plunge and devote some inventory to it.