How to run your own prediction market to bet with friends

Short answer: Create a free private market on the Vancouver Prediction Exchange, share the invite link with your group, and everyone trades YES and NO shares with the same play money until the answer is known. No deposits, no payouts, and it takes about ten minutes.

Every friend group has running arguments. Whether it snows on Christmas. Whether the ski trip happens. Whether Dad fixes the fence. Someone says "wanna bet?", a number gets tossed around, and by February nobody remembers the terms.

A private prediction market settles it. Everyone gets the same play money, trades YES and NO shares on the question, and the price moves as people back their opinions. When the answer comes in, the host settles and the standings show who called it.

The screenshots below use a real market, "Will it snow in Vancouver on Christmas Day?", with Maya hosting and her friends Bob and Carol joining. Follow along with your own question.

The basics in 30 seconds

It is all play money. Nobody deposits, nobody cashes out. You play for the top of the standings. Four ideas cover it:

• Shares. Every question has YES and NO shares. At settlement, each share on the winning side pays $1.00 and the losing side pays nothing.
• Prices. Shares trade from 1¢ to 99¢. A YES price of 40¢ means the group sees about a 40% chance of yes. Buy YES at 40¢ to make 60¢ a share if you are right, or lose the 40¢ if you are wrong.
• Play money. Everyone gets the same starting balance, and it exists only inside this market.
• Settling. When the answer is known, the host picks the outcome and VPX pays everyone out.

To follow along you need a free VPX account, a yes or no question with a clear answer and a date you will know it by, and a couple of friends.

Step 1: Create your market

Sign in and open the VPX home page. The Private Markets section near the top has a plus button on the right.

The plus opens the create form.

• Market question. One sentence with a yes or no answer. "How much will it snow?" does not work, because there is no single answer to pay out on.
• Description / rules. The box people skip and the one that matters. Write exactly how you decide, with the source and the edge cases. Ours resolves YES if Environment Canada records any snowfall at YVR on December 25.
• Outcome labels. Default to YES and NO. Rename to "Snow" and "No snow" if it reads better.
• Trading opens and closes. Leave "opens" blank to start now. "Closes" is when betting stops. Times are Eastern.
• Resolution date. When you expect the answer. Members see it.
• Starting funds. The play money everyone gets. We left it at $10,000.
• Access code. A short word friends type to join. We used SNOWDAY. Leave it blank for a random one.
• Lit market. Leave it checked so everyone sees who traded with whom. Untick for a dark market with no names on trades. Standings are named either way.

Click Create private market for the invite link and access code.

Go to market shows it live: the private market banner with the link, code and Manage button, the question, an empty order book, and the standings with just the host.

Step 2: Invite your friends

Three ways in, and you can use all three at once:

• Invite link. The easiest. Drop it in the group chat. A friend without an account signs up with your market at the top and joins on the spot; a signed-in friend is added straight away.
• Access code. For friends already on VPX. They open the market page and type the code. Bob typed SNOWDAY and pressed Join market.
• Request access. The fallback under the code box. Someone with no code sends you a short message to approve on your Manage page.

New members land on a confirmation of their play money balance. Here is Carol, in through the invite link.

Step 3: Place a bet

The trade panel sits on the right of the market page, or below the chart on a phone. Pick YES or NO at the top, then Buy, Sell or Redeem, and toggle MARKET or LIMIT.

A market order takes the best price on offer. A brand new market has no offers yet, so the first trades are limit orders: "buy this many shares at this price or better." Set your price in cents and quantity in shares.

Maya thinks snow is likelier than her friends do, so she buys 1,000 YES at 40¢. That is $400, and if it snows those shares pay $1,000 back, a $600 profit.

She clicks Buy YES. Nobody has taken the other side yet, so the order rests on the book and waits.

Someone takes the other side

Bob is a skeptic: Vancouver gets rain at Christmas and the snow stays on the mountains. He picks NO and buys 1,000 NO at 60¢.

Here is the neat part. Maya offered 40¢ for YES, Bob offered 60¢ for NO, and 40 plus 60 is 100. Together they put up the full $1.00 that a YES and a NO share are worth as a pair. So VPX pairs the orders: $400 from Maya, $600 from Bob, 1,000 YES to Maya and 1,000 NO to Bob. VPX calls this a marriage, and it shows up in the Recent activity feed.

One of them ends up with $1,000 and the other with nothing. The price settles at 40% YES, the last price they agreed on. The marriage and divorce wiki page has the longer version.

Reading the order book

Carol figures snow is a little likelier than 40% and bids 500 YES at 45¢. Maya hedges and bids 500 NO at 50¢. Neither order matches yet, so both rest.

On the Trade YES tab:

• Bids are offers to buy YES. Carol's 45¢ bid sits here.
• Asks are offers to sell YES. Maya's NO bid shows up here as a 50¢ ask, because paying 50¢ for NO is the same as letting someone have YES for 50¢.
• Spread is the gap between the best bid and the best ask, 5¢ here. Last is the most recent trade.

You never have to read the book to trade. The buttons at the top of the panel always show the current price for each side.

Keeping score

The Standings card under the order book is the leaderboard.

• Cash is play money not tied up in shares.
• Holdings is what your shares are worth at the current price.
• Net worth is the two together, and P&L is how far that sits above or below your starting funds.

Everyone is at $10,000 for now, because nothing has settled and shares are marked at the price they were bought for. Bob then buys 500 more NO at 55¢, which marries Carol's 45¢ YES bid. Back the side you believe in and wait for the answer.

Step 4: Manage the market

The Manage button in the banner is your control panel. The Overview tab has the invite link, access code, a button to regenerate the link if it leaks, a box to change the code, and any pending access requests.

The other tabs:

• Settings. Edit the question, rules, labels, dates and starting funds, and switch between lit and dark.
• Members. Make someone an admin, remove a member, or top up their play money if they blew through it early.
• Activity. The full trade log.
• Trading. Pause and settle.

The Trading tab also has Halt trading (block new orders, keep the book), Close trading (cancel every open order and stop, reopen later), and Cancel all open orders (clear the book without closing).

Step 5: Settle and crown a winner

Christmas morning arrives and, in our story, it snows. Open the Trading tab, click Settle market, pick the outcome that happened, add a short note, and confirm. You can settle before the close date if the answer comes early.

Settling cannot be undone, so double check the outcome. Any orders still on the book are cancelled and their play money returned, so Maya's 50¢ NO bid comes back. The market page shows the result and your note.

Where the money went:

• Maya paid $400 for 1,000 YES shares. Each paid $1.00, so she took $1,000 back and finished up $600.
• Carol paid $225 for 500 YES at 45¢. They paid $500, so she finished up $275.
• Bob paid $600 for his first 1,000 NO and $275 for the next 500. NO paid nothing, so he finished down $875.

The winners' gains equal Bob's loss. Play money only ever moves between members.

Good questions to bet on

The best questions are the ones your group already argues about:

• Will it snow on Christmas Day? Weather is a great starter, the source of truth is obvious.
• Will the group trip actually happen this season?
• Will Dad fix the fence by Christmas?
• Will the office get the new espresso machine before year end?
• Will the friend who "isn't seeing anyone" bring a date to the wedding?

Write the rules as if the most argumentative person in the chat is going to read them: name the source, cover the edge cases, and give a date.

Common questions

Is this real money? No. Private markets use play money only. Nothing is deposited or paid out.

How many people can join? As many as you send the link or code to. We used three so the screenshots stay readable, and thirty works the same.

What if someone joins late? They get the same starting funds. Prices may have moved by then, which is part of the fun.

Can I settle before the close date? Yes. If the answer becomes known early, settle whenever you are ready.

Can members see what I bet? In a lit market, yes, the activity feed shows names. In a dark market, trades show without names, though admins still see everything and standings are always named.

What if the question can't be answered? Write that case into your rules up front, for example "resolves NO if the trip is postponed to next year." For anything truly unforeseen, halt trading from the Manage page and talk it over with your members before you settle.

That is the whole loop: create, invite, trade, settle. The first market takes about ten minutes to set up, and the second one takes two. To go deeper on how prices and orders work, the order book wiki page is a good next read.