Glossary
What is Bid shading?
Also called: shading
Bid shading is when a buyer bids below its true value in a first-price auction, aiming to pay just enough to win.
हिंदी में पढ़ेंIn a first-price auction the winner pays what it bids, so bidding full value means overpaying. Bid shading is the DSP technique of lowering a bid towards the price that is likely to win. The buyer’s software learns what usually clears on a site and bids just above it.
Shading matters because exchanges moved from second-price to first-price auctions; Google Ad Manager completed its move in 2019. Google also shares a minimum bid to win with buyers after Ad Manager auctions, which gives shading models more data to learn from.
For publishers, shading means lower bids do not always mean weaker demand. A buyer may value your inventory as much as before but simply have learned that it can win for less. What pushes shaded bids back up is more real competition and floors set close to what buyers really value.
Example
A buyer values an impression at $5.00. Its model sees that $3.20 usually wins on this site, so it bids $3.20. If it wins, it pays $3.20 rather than $5.00, saving $1.80 CPM.
Why it matters to publishers
Shading explains why bids can drop without any change on your site, and why competition and well-set floors are your main answers.