Ad Exchange
An ad exchange is the neutral programmatic marketplace where publishers' supply and advertisers' demand meet, running the real-time auctions that match bid requests with bids.
Key takeaways
- An ad exchange is the marketplace that matches buy and sell bids in real time.
- It runs on RTB and the OpenRTB protocol.
- SSPs and DSPs connect through the exchange; it is not the same as either.
- Supply-path optimization exists partly to reduce redundant exchange hops.
The marketplace layer
The ad exchange receives a bid request from the supply side, broadcasts it to connected DSPs, collects bids, resolves the auction, and returns the winner. In principle it is neutral infrastructure; in practice many exchanges are operated by companies that also run SSP or DSP functions, which complicates that neutrality.
Why supply paths multiply
Because the same impression can reach a buyer through several exchanges and resellers, the same opportunity often appears multiple times in an auction. The SupplyChain object and sellers.json expose those paths so buyers can run supply-path optimization and prune redundant, fee-heavy routes.
| Role | Neutral programmatic marketplace |
|---|---|
| Runs on | RTB / OpenRTB |
| Connects | SSPs (supply) and DSPs (demand) |
| Transparency tools | sellers.json, SupplyChain object |
Frequently asked questions
What is the difference between an ad exchange and an SSP?
An SSP represents and optimizes a publisher's supply; the ad exchange is the marketplace that matches that supply with demand. Many platforms perform both roles.
Why do the same impressions show up on multiple exchanges?
Publishers connect to several supply paths, so one opportunity can be resold across exchanges. Supply-path optimization uses the SupplyChain object to consolidate these into the cleanest, cheapest route.