How to Diagnose a Sudden Change in Programmatic Inventory Mix
A change-point checklist for sudden shifts in pharma programmatic domain, app, or deal mix, tied to likely causes and the evidence that confirms each.
The short answer
One week a campaign delivers mainly on endemic health sites. The next week half the impressions are on mobile games. Sudden inventory mix changes are common in programmatic, and they can hurt quality and performance quickly. Finding the cause fast matters. A change-point checklist helps.
First, confirm the change
Compare the domain and app mix for the week before and the week after the change. Look at:
- Top 20 domains or apps by impressions
- Share of spend by inventory type: web, app, CTV
- Share by deal versus open market
- Share by exchange
Make sure the change is real and not a reporting artifact, such as a new report format.
Then check likely causes
| Possible cause | Evidence to check |
|---|---|
| Targeting or setup change | Change log in the DSP; who edited what and when |
| Deal stopped delivering | Deal-level delivery; floor price changes; seller notices |
| Bid or budget change | Bid history; pacing settings |
| Blocklist or allowlist change | List versions and last update |
| Data segment change | Segment size history; partner notices |
| Exchange or seller issue | Delivery by exchange; seller changes in sellers.json |
| Seasonal or market change | Other campaigns showing similar shifts |
| Supply-side fraud or spoofing | Invalid traffic rates; ads.txt authorization of new sources |
Work through the table in order. Setup changes are the most common cause and the fastest to confirm.
Act on the cause, not the symptom
- If a deal stopped delivering, budget flowed to open market. Contact the seller and consider pausing open-market fallback.
- If a blocklist was removed or failed, restore it and check for similar gaps.
- If new unauthorized sources appeared, block them and review the path. See ads.txt, sellers.json, and schain.
- If bids were raised to fix underdelivery, the new inventory may be the result. See underdelivery diagnostics.
Prevent the next one
- Keep a change log for every campaign.
- Set alerts for large shifts in top domains or inventory type.
- Review the mix weekly as part of weekly optimization.
- Keep backup supply paths for critical inventory. See supply path optimization.
Escalate when needed
If the shift involves possible fraud, brand safety exposure, or significant spend on unsuitable inventory, use a formal partner escalation process.
Practical takeaway
Save a weekly snapshot of your top domains, inventory types, and exchanges. When a shift appears, compare snapshots, check the DSP change log first, and work down the cause table.
Sources
External guidance and platform documentation change. Links were current at publication; check them again before relying on them for a decision.
Editorial note. Analysis and frameworks are the author's own and do not represent Acxiom or any current or former employer, client, or named platform. Examples labeled hypothetical or illustrative are not results from real campaigns. Nothing here is legal, regulatory, or medical advice.
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