Remnant
Leftover inventory that was not reserved. Open-exchange display is remnant. It is useful for tests and easy to misread.
Remnant is the inventory that remains after reserved and preferred paths take their share. Open-exchange banners are remnant. They are cheap to test against and noisy to judge.
Leftover slots produce clicks readily. That is why CTR on remnant looks more informative than it is. Our August 2026 Supply Bench pull showed 93.4 percent of placements with zero clicks taking 64 percent of spend, and seven domains producing 41.3 percent of clicks from 4.7 percent of impressions. msn.com repeated a high CTR across flights. No IVT vendor was attached.
Remnant is a classroom for isolated funnels and supply-grain excludes. It is a poor classroom for "the brand is working" stories. Judge it on our first-party traffic grade: real visits to the landing page, bot traps, and engagement on that page. Click-to-page-view is one input (15.85 percent usable and 3.75 percent poor on anonymized brand-name display campaigns from Adprime's managed ad operations), and a vendor IVT tag is a hint.
See CTR is a trap and the Supply Bench scorecard.