You Can Mock Trade With A Deck Of Cards

Here’s a mock trading game I learned as a trainee to simulate futures and options market making. This game was commonly used as a day 1 exercise in trading class or when interviewing cohorts of college grads during recruiting “combines”.

The Futures Game

What you need:

1. A deck of cards
2. Nerdy friends (the more the better)
3. A paper and pen per person to use as a tradelog

Setup:

You want to deal out enough cards to players (these are the market makers) so that there is about 25 remaining in the deck. There’s some leeway here.

Example:

• You have 6 players. So deal them each 4 cards leaving 28 cards undealt.
• Market makers may look at their hands but don’t share info.
• The undealt cards are known as the “public pile”. They should be evenly divided into 4 or 5 sub-piles ideally (again there’s leeway depending on how many cards there are).
• The sub-piles are going to represent “trading days”.
• The cards themselves are news flow which will move the futures prices.

Description of futures prices:

• The futures are the 4 suits. There’s a club’s market, a spades market, etc.
• The final settlement price of the futures will be the sum of the ranks of cards in the public pile. (Ace =1 thru King = 13). So the maximum any future can be worth is 91¹
  It’s best to define the tradeable universe to keep the liquidity centralized.So you could have a diamond market, a spades market, and a “reds” market (which would be an index settling to the sum of diamonds and hearts).

How To Play

The first trading day

• Reveal the cards in the first public sub-pile.
  
• Market makers make bids and offers for the various markets. Tight 2 sided markets should be encouraged/required. For example:
  
  John: “I’m 65 bid for Hearts and offered at 68”Jen: “I’ll pay 67 for 5 Hearts contracts” (perhaps Jen is holding no Hearts in her hand)John: “Sold you 5 at 67” (John is holding 16 points of Hearts in his hand)
  
• Record all your trades on your own pad or paper:
  
  1. Which contract you bought/sold
  2. Quantity of contracts
  3. Price of contracts
  4. Counterparty

So for example, if I paid 51 for 4 “clubs contracts” from Mary I would record that information on my paper. Mary would record her sale of the 4 contracts at 51 on her card with me as the counterparty.

• The trading is open outcry. There are no turns.

Settling the trading day

1. When the trading peters out for that “day” everyone should check their trades against their counterparties to make sure there are no so-called breaks or “outtrades”.
2. On a central eraseboard or paper the “closing price” of each market can be recorded. So if the King of clubs and 3 of clubs were revealed from the sub-pile, then clubs “settled at 16”. Clubs might have traded 53 last in the expectation that more clubs will be revealed on subsequent days.
3. Repeat this process for all remaining tradings days

The last settlement

• Compute “P/L” for all trades.

If I bought 4 clubs contracts for $51 and clubs final settlement was $63 then I made a profit of $12 x 4 or $48. Mary’s loss would match that amount for that trade.

The total P/L of all traders should sum to zero at the end of the game.

Options Variant

• Either the same group or a different group of people could choose to trade calls and puts on the final settlement price of the futures.
  So if I paid 3 for Clubs 55 calls and the final settlement was $63 then I profit the difference between the $63 and the strike ($55) minus the premium I outlayed:
  $63-$55 – $3 = $5
  
• You could even get fancy and trade “vol”. You could sell say 10 clubs calls and buy 5 clubs futures to hedge the delta.
  
• This game is played the same way the futures game is played or in conjunction. Repeat the process for all trading days then compute P/Ls at the end. Again if there are no errors the game should be zero-sum.

Footnotes

1. Here’s the trick to summing the numbers 1 through N or in this case 1 thru 11.

N(N+1)/2

So 11×12/2 = 66

Let’s try another. Sum the numbers 1 through 100.

100×101/2 = 5050

Why does this work?

Pair the ends off.

100 + 0
99 + 1
98 + 2
97 + 3
96+4
…continue until 51+49

What do you end up with:

• 50 pairs summing to 100
• The middle “50” left over.
  
  50×100+50 = 5050.
  That maps to (N/2) x N+1 or “the middle number occurs N + 1 times”. That 1 term is the “middle 50”.