<b>Loss reason codes are the most underused field in the bidstream</b>

<b>Loss reason codes are the most underused field in the bidstream</b>

When you lose an auction, many exchanges return a loss reason code: a small integer telling you <i>why</i> you lost. Most teams discard it. It is arguably the highest-signal field in log-level data.

1. Codes broadly split into 'lost on price' (you bid, someone bid more) and 'lost for non-price reasons' (creative rejected, below floor, bidder timeout, blocklisted advertiser, currency mismatch).
2. Aggregate the codes for a campaign that's underdelivering. If 70% of losses are non-price, raising bids does nothing — you are being filtered for a creative or eligibility reason.
3. 'Below floor' as a dominant code means the publisher's floor exceeds your bid; that's a targeting or PMP-negotiation problem, not a bidding problem.

The trap is that win-rate dashboards lump all losses together, so a campaign losing on creative policy looks identical to one losing on price. The reason codes are the only thing that separates them cleanly.

<b>Why it matters:</b> before you change a bid, pull the loss reason distribution. A surprising share of 'we can't win this inventory' problems are creative rejections or floor mismatches that no amount of money fixes. The field is already in your feed — wire it into your reporting.