The Market Game

Post a price · count the cards · let the market find equilibrium
Scenario Base market Round 1
Posted price this round
$6
Market avg price
—
Units traded
0
Count the raised cards, enter them below, then lock in the round.
Cards raised at this price
Buyers — Demand
Sellers — Supply
Pre-filled with what the cards should show — adjust to the real count if the class plays it differently.
Trade lottery · who trades on the long side
Draw pool — tap a card to leave it out of the draw
Draw
Price sensitivity · k
Restart the market
Start price
The price moves toward balance each round: next = price + k×(Demand−Supply). Values are packed close to $10, so nearly every card trades. From the $6 start the price climbs gently to equilibrium (e.g. $6 → $8 → $9 → $10) and settles. Quick (k=0.25) takes bigger steps if you're short on time.
The market, live

Demand & supply — where does the price sit?

Demand Supply Price
Round history
RoundPriceDemandSupplyTradesResult
No rounds yet — lock in the first one.
Scoreboard
Trade a round and the market's average price appears here.
▸ How to play & the price rule

Half the class are buyers (each holds a private value — the most they'll pay), half are sellers (each holds a cost). Everyone has 3 units to trade, at most one per round. Each round:

  1. Read the posted price. If it's worth it, raise your card to trade a unit — buyers when price ≤ value, sellers when price ≥ cost. Holding out for a better price is allowed.
  2. Count the raised cards — Demand and Supply — and type them in.
  3. Pair up and deal at the posted price; min(Demand, Supply) deals happen. Traders write the price on their card. Lock in the round.

The price then moves in proportion to the imbalance:

next price = price + k × (Demand − Supply)

A shortage pushes the price up, a surplus pushes it down, and when Demand = Supply the price holds — its equilibrium. Score by your average price: buyers want the lowest, sellers the highest. Watch the market average converge toward equilibrium even though trades happen at many prices.

Every card's value sits within a few dollars of $10, so almost everyone trades. From the $6 start the price climbs a step at a time (about $6 → $8 → $9 → $10) and settles once Demand = Supply. Early birds who buy at $6–$8 pay below normal, and late sellers who hold to $10 do best; that spread is the contest. Only the single most-marginal card on each side may sit out, and you can hand them a unit with the draw below.