Hi, I'm very new to programmatic (have previously *bought* GDN, Google Search, Facebook and Taboola, but have virtually no experience on the publishing side).

I'm working with a publisher that currently receives about 30M monthly organic pageviews and is only running Adsense and Taboola for monetization. They are fairly brand sensitive and want to move to a white list of advertisers with direct relationships. My understanding is that this is called a "private marketplace" and that big DSPs like The Trade Desk support this use case, where basically all the parties involved create "Deal" entries and then the whole thing is configured to run an auction where only the invited advertisers get to participate.

However, I'm really very ignorant as to how a publisher would even go about arranging something like this and what the options are (especially if there are companies smaller than The Trade Desk that are easier to work with for this kind of problem, or what kind of minimum requirements are needed in terms of volume to be eligible). The important thing from the publisher side is that they want to be able to have an invited whitelist of advertisers (but none of the publishing networks I'm familiar with, like Taboola, seem to offer this option, it's all just an open auction).

Can anyone give me a high level overview how to approach this problem? I'm familiar with how to create and run buyside campaigns, but I'm really out of my depth here.