How It Works

Play-money system

All activity on Predimarkt uses fictional balances. You start with an initial balance and use it to trade on events. Everything runs on play money, allowing you to focus on reasoning, information, and judgment without financial risk. There are no deposits, withdrawals, or real-world rewards. You can't earn real money — but you also can't lose it. Your balance simply reflects how accurate your predictions have been over time. Balances may go negative. This allows you to fully participate in markets, including taking positions that may later turn out to be incorrect.

Prediction markets

Each market represents a question about a future event. It includes a set of possible outcomes (assets), and each outcome has a price that reflects its current estimated probability. By trading — buying or selling outcomes — participants collectively shape these probabilities. As new information becomes available, users make new trades and prices update to reflect changing expectations.

Trading

Trading is continuous and flexible. You can act at any time:

• Buy an outcome if you believe it is more likely than the current price suggests
• Sell an outcome if you believe it is less likely than the current price suggests

In binary markets, buying "Yes" is equivalent to selling "No," and vice versa — though the framing may differ in how you think about the trade.

When buying, you spend money now and profit if the outcome happens. But you can sell at any time to cut losses or take profits before resolution. This allows you to adjust your position as the situation evolves. You can also short sell (sell assets that you don't own yet). In this case, you receive money immediately, and this is your maximum possible gain — but if you're wrong, you may have to pay back more later.

Predimarkt uses an automated market maker based on the logarithmic market scoring rule. This means:

• You can always trade instantly — there are no bids or asks, and liquidity is always available
• Prices adjust smoothly with each trade, so the total cost is not simply "price × quantity"
• The price you pay varies within a trade: earlier shares are cheaper, and later shares reflect the updated probability

Creating a market

Anyone can create a market. With that comes responsibility. A well-created market should be:

• Clear — the title should be short, informative, and unambiguous
• Well-defined — the description must explain exactly how the outcome will be determined
• Verifiable — resolution should rely on publicly available information whenever possible

When creating a market, you should:

• Write a clear title
• Provide rules and description, including definitions and resolution criteria
• Optionally include references to sources
• Set the intended market closing date and time (in your local time)
• Define the possible outcomes (assets)
• Assign short, unique symbols for each outcome (used in charts)
• Set initial probabilities to reflect your best estimate at the time

The closing time determines when trading will stop. Markets are automatically closed at the scheduled time, but the creator may close a market earlier if necessary (for example, if the outcome becomes known sooner than expected). Once closed, a market can be:

• resolved (when the outcome is known)
• refunded (if the market cannot be fairly resolved)
• re-opened with a new closing date and time

Setting reasonable initial probabilities is important — large inaccuracies can create unfair advantages for early traders. Creators are also expected to avoid immediately taking large positions in their own market to exploit initial pricing.

Responsibilities of market creators

Market creators act as stewards of their markets. They are expected to:

• Treat participants fairly and respectfully
• Keep rules clear and consistent
• Update descriptions if clarification is needed (without changing the core meaning)
• Monitor the event and resolve the market promptly once the outcome is known

Market Resolution

A market should be resolved when the outcome can be clearly determined based on the rules and description provided at creation.

• The selected outcome must match the predefined resolution criteria
• Resolution should be based on reliable, publicly verifiable information whenever possible
• The creator should act in good faith and follow the stated rules

Once resolved, the market is final and cannot be changed.

Market Refunds

A market should be refunded if it cannot be resolved fairly or unambiguously.

This may happen, for example, if:

• The question was unclear or poorly defined
• The resolution criteria were missing, incomplete, or contradictory
• The outcome cannot be determined with reasonable certainty
• The underlying event did not occur or became irrelevant

When a market is refunded, all participants receive their funds back as if no trades had taken place.

Re-opening a market

If a market was closed too early or needs more time, it can be re-opened by setting a new closing date. Trading will resume, and the market can later be closed and resolved as usual. Creators are expected to use this option responsibly and avoid changing timelines in a way that could disadvantage participants.

Leaderboard and goals

The leaderboard highlights the top participants, based on performance adjusted over time. It accounts for factors like consistency and duration, rather than just total accumulated gains. However, the goal of Predimarkt is not to "win" the leaderboard. There are no material rewards. The real value comes from improving your judgment, learning how to reason under uncertainty, and understanding how information shapes expectations.

Final note

Predimarkt is an educational platform. It does not provide financial or investment advice, and nothing on the platform should be interpreted as guidance for real-world decisions.