The Trustworthy Accountability Group, the Association of National Advertisers and the technology firm Fiducia today published an analysis quantifying the share of programmatic advertising spend flowing to AI slop, finding it accounts for between 1.3% and 2.4% of open web programmatic investment. That range sits close to the 1.1% measured for made-for-advertising inventory in the same quarter.

The finding that will occupy buyers, however, is not the size of the problem. It is the direction of the quality signals. According to TAG, slop inventory recorded an invalid traffic rate of 0.05% against 0.32% for clean supply, viewability of 77.2% against 74.9%, and, once measurability was accounted for, graded as premium more than 70% of the time. Those scores translated into higher prices: a TrueCPM of $7.08 for slop against $6.15 for clean inventory.

The work forms part of the Q1 2026 ANA Programmatic Transparency Benchmark, a joint initiative of TAG TrustNet, Fiducia and the ANA. It was conducted and drafted by Scott Cunningham of Cunningham.tech Consulting.