When it came on to the scene, so-called “programmatic” advertising was all about real-time bidding in open online marketplaces. That meant advertisers often didn’t know where they were buying ads – a far cry from the old days of manual display sales.

Over time, the industry has evolved to ringfence sections of the web in to the kinds of trusted destinations they want to do business. But what are these “private marketplaces” and how do agencies use them?

In a Beet.TV panel discussion, GroupM Connect North America chairman John Montgomery offered up one of the handiest descriptions yet:

“We’ve created trusted marketplace with a group of several hundred partners that we know that represent tens of thousands of sites,” he said. “We buy inside that environment – we know we can get the reach in that environment.

“We are buying media programmatically within an environment of people that we know. We’ll create preferred marketplaces within the trusted marketplace for auto, for healthcare, for luxury goods.

“Yes, we may occasionally have to buy outside that trusted marketplace if we can’t get the reach. But, generally speaking we know that marketplace is (for example) 70% safe and we make sure we use viewability, verification anti piracy companies to make it 99% safe.”

Montgomery was questioned by moderator Tobi Elkin.

We interviewed him at Media Future Conversations 2015: Unblocked – Valuing Human Attention In A Content-Driven World, an event presented by true[X] in association with Beet.TV Please find more event videos here.