Reference library · Inventory pricing
SSP (Supply-Side Platform)
A Supply-Side Platform (SSP) is the auction technology a publisher uses to sell its ad inventory programmatically to multiple demand sources at once. From the buy side, the same impression is often reachable through several competing SSPs, so a planner's job is managing how many SSPs a desk trades through, since each one charges its own platform fee and adds a redundant auction path for inventory another SSP already covers.
Worked example
A buyer runs €500,000 of monthly programmatic display through 10 SSPs at €50,000 each, paying the list tech fee of 20% (€100,000/month in fees, leaving €400,000 of working media). A log-level audit shows 3 of the 10 SSPs already cover the same publisher inventory as the other 7, so the buyer consolidates onto those 3, concentrating volume and negotiating the fee down to 14%. On the same €500,000 spend, fees drop to €70,000, putting €430,000 to work instead of €400,000, a 7.5% gain in working media with no loss of reach.
How it is used
Trading desks run periodic SSP rationalization: pulling bid-request logs to see how much unique inventory each SSP delivers versus how much overlaps with SSPs already in the stack, then dropping platforms that add fee cost without unique reach. Fewer SSPs also means higher volume per platform, which is the lever used to negotiate the tech fee down from list rate. The mistake practitioners make is treating SSP count as a reach lever, adding platforms because a rep pitches unique publisher access, without checking log-level overlap first.
The common mistake
The common error is adding SSPs for claimed reach without checking log-level overlap, which dilutes fee-negotiating volume rather than adding inventory.