A 5-step playbook to audit your supply path before cutting SSPs

A 5-step playbook to audit your supply path before cutting SSPs

Supply path optimization (SPO = consolidating onto the cleanest, shortest routes from DSP to publisher) fails when you cut paths blindly. Run this sequence first.

1. Pull 14 days of log-level data and group impressions by the tuple (publisher domain, SSP, seller_id from sellers.json).

2. For each tuple compute three columns: win rate, median clearing price, and the share of impressions carrying a direct or reseller flag in the supply chain object.

3. Find duplicate paths — the same publisher reachable through 3+ SSPs. These are your resell chains where one impression is auctioned multiple times.

4. Rank duplicate paths by effective cost: not the bid, but (winning_price + ssp_fee) divided by post-bid quality (viewability, IVT rate).

5. Keep the single cheapest qualifying path per publisher; throttle the rest to 5% spend for two weeks to confirm no win-rate cliff before full cut.

The mistake is cutting on volume. A high-volume path that loses 80% of auctions to a cheaper twin is pure auction noise inflating your QPS bill.

Why it matters: SPO done on log-level evidence rather than SSP reputation typically recovers 8-15% of working media without touching creative or targeting — it's the highest-leverage, lowest-risk optimization most buyers skip because the data join is tedious.