Bid-ask paper market
Match voluntary bids and asks while respecting private reservation limits.
Cooperation & communication
- Players
- 4 players
- Time
- 15–20 minutes
- Materials
- Private buyer values 6,8 and seller costs 2,4; two unit cards and public offer ledger.
Prepare
Assign two buyers private values 6 and 8 and two sellers private costs 2 and 4. Each seller owns one fictional unit; each buyer can buy at most one. Choose clockwise order before revealing any offers. Private values remain hidden until the end; these are game numbers, not prices or financial advice.
Play
Across eight total turns, an unmatched buyer may post or replace one bid no greater than their value; an unmatched seller may post or replace one ask no lower than their cost. Whole-number prices 0–8 only. Anyone may pass. A new offer replaces only that person’s old offer, and a completed trader takes no further market action.
Worked example
After posting, the active player may accept one standing opposite offer that fits both limits. A buyer accepts a seller’s ask at that ask price; a seller accepts a buyer’s bid at that bid price. Both confirm the trade and remove their offers and one unit. A crossed bid and ask alone do not transfer a unit without this acceptance.
Finish and check
Buyer value 8 accepting ask 5 from seller cost 2 earns 3 surplus; the seller earns 3. Buyer value 6 offering 7 is illegal even if no trade occurs. After eight turns or two trades, reveal values and score each buyer value minus paid price and each seller received price minus cost. Unmatched players score 0; highest surplus wins, ties shared.
Adaptation and limits
The ledger records offer owner, time, price and acceptance, so two offers cannot claim the same unit. No debt, real payment or penalty for refusing. A recorder can handle arithmetic. This small paper market demonstrates specified trading constraints, not real-world efficiency or a promised profitable strategy.
Purpose, observation and provenance
Within this activity: Match voluntary bids and asks while respecting private reservation limits.
Explain one legal decision and check it against the written constraints; a single result does not measure lasting ability.
Our rules, examples and printable diagrams are separately prepared. The earliest inventor of the broader mechanism is not established here.
Free alternative: Copy the supplied grids, labels and cards onto reused paper. No specialist product is needed. Adults may prepare pieces or act as a scribe.
Printable materials
Preview at 100% scale, with browser headers and footers off. Cut with suitable help. Keep host keys separate. This is a manual tabletop kit, not an online opponent, automatic judge or solver.
Player materials · Bid-ask paper market
Buyer values 6/8; seller costs 2/4 — private role cards.
Turn / owner / bid or ask / price / accepted by / unit / surplus.
Keep private role cards on the separate page face down until assigned. Two public units: U1,U2.
Additional pieces / private cards
Player record · keep host key separate
| Turn/owner | Bid/ask | Price | Accept/trade |
|---|---|---|---|
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
Host key · separate from players
Value 8, cost 2, trade 5: surplus 3 each. A buyer may not bid above own value; a seller may not ask below cost.
Run the round
Assign two buyers private values 6 and 8 and two sellers private costs 2 and 4. Each seller owns one fictional unit; each buyer can buy at most one. Choose clockwise order before revealing any offers. Private values remain hidden until the end; these are game numbers, not prices or financial advice.
Across eight total turns, an unmatched buyer may post or replace one bid no greater than their value; an unmatched seller may post or replace one ask no lower than their cost. Whole-number prices 0–8 only. Anyone may pass. A new offer replaces only that person’s old offer, and a completed trader takes no further market action.
After posting, the active player may accept one standing opposite offer that fits both limits. A buyer accepts a seller’s ask at that ask price; a seller accepts a buyer’s bid at that bid price. Both confirm the trade and remove their offers and one unit. A crossed bid and ask alone do not transfer a unit without this acceptance.
Buyer value 8 accepting ask 5 from seller cost 2 earns 3 surplus; the seller earns 3. Buyer value 6 offering 7 is illegal even if no trade occurs. After eight turns or two trades, reveal values and score each buyer value minus paid price and each seller received price minus cost. Unmatched players score 0; highest surplus wins, ties shared.
The ledger records offer owner, time, price and acceptance, so two offers cannot claim the same unit. No debt, real payment or penalty for refusing. A recorder can handle arithmetic. This small paper market demonstrates specified trading constraints, not real-world efficiency or a promised profitable strategy.