ADX / Exchange

Exchanges receive bid requests describing an impression opportunity, solicit or receive bids from DSPs / buyers, apply auction rules (first-price, second-price legacy paths, floors, deals), and return a winner to the seller stack.

They also:

• Enforce creative / brand-safety policies where configured.
• Emit loss notices and diagnostics when bids fail.
• Connect many SSPs on the sell side to many DSPs on the buy side.

Think of the exchange as the clearing house, not the media owner or the campaign strategist.

Marketplace health shows up in auction mechanics:

• Bid request / Bid response volume and density.
• Win rate — how often a bidder’s response wins.
• Auction latency — time to clear without hurting page load.
• Floor price interaction with clearing price.
• CPM / clearing prices as market signals.

Buyers and sellers both read exchange stats — but each cares about a different slice of the same auction.

• SSPs bring publisher inventory and seller constraints.
• DSPs / advertisers bring bids and campaign goals.
• Verification vendors may wrap the impression for viewability or IVT.

If win rate drops, the cause might be floor changes, competitor bids, creative blocks, or timeout — not a single “ADX is broken” story.

• Confusing exchange with SSP or DSP (different jobs in the same flowchart).
• Reading win rate without the vendor’s denominator definition.
• Ignoring loss reason codes when diagnosing spend gaps.
• Assuming second-price intuition in a mostly first-price world.