Auction Lab

The budget runs out

Twenty impressions, real budgets, fresh values each round. One bidder spends until they are broke; the other paces itself and is still bidding at the end.

Run with First-price sealed bid. The link below opens this over repeated rounds, where the bidders adjust as they learn. Here is the first round on its own.

BidderWorth to themBid
A7070
B7070
C7070

Step by step

  1. collect bids Each bidder submits one sealed bid; private values are never revealed.
  2. sort Bids are ranked from highest to lowest. Equal bids keep the order the bidders were listed in, so a tie goes to the first-listed bidder.
    70 >= 70 >= 70
  3. pick winner The highest eligible bid wins the item. 3 bidders tied at 70; the tie goes to A because they were listed first.
    argmax b_i = A at 70
  4. price rule The winner pays exactly what they bid, so every unit of bid above the runner-up is money left on the table. That is why bidders shade their bids below their true value here, and why the bids you see are not values.
    p = b_i = 70
  5. payments A pays their own bid of 70; the losers pay nothing.
    revenue = 70

How it came out

WinnerA
Price paid by the winner70
Seller revenue70
Value created70
Went to whoever valued it mostyes
BidderPaidEnded up with
A700
B00
C00

Open this example in the walkthrough

The link carries the whole setup, so you can change a bid and watch what moves — and send the result to somebody else.

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