By James Hercher
Publication Date: 2026-01-26 17:28:00
Most publishers have no idea that a major part of their video ad delivery will stop working on April 30, shortly after Microsoft shuts down the Xandr DSP.
For publishers that rely on Prebid and Google Ad Manager, the effects could be immediate and costly.
When an advertiser wins a video ad impression in a Prebid auction and the publisher uses Google Ad Manager (GAM), Google runs a secondary auction that compares the Prebid bid against bids from its own demand stack.
If the Prebid bid wins, GAM calls for the video creative to be served.
This all happens in microseconds.
But for that brief moment before GAM makes the final auction decision, an intermediary must host the video ad file coming from Prebid. To date, these storage costs have always been taken care of on behalf of publishers, initially by AppNexus, then by Xandr within AT&T and, now, by Microsoft Advertising, which bought Xandr in 2021.
But, as of the end of…
