Price fairness

The commitment

Before a house index starts, we create a chain of secret seeds, one for each day for ten years, and publish the hash at the end of the chain. Each day's seed hashes to the previous day's, and the first day's hashes to this commitment. Nobody can find a seed that fits the chain without already having it, so every future price was fixed when the commitment was published.

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Keep a copy of the commitment. It stays the same for the whole ten years of the chain. If it ever changed, every check you'd done before would stop matching.

How each price is made

House indices tick once a second. For the tick at second t (Unix time):

1. day is the number of whole UTC days since the chain's launch day, starting at 0.
2. seed is that day's seed: 32 bytes that give the commitment after day + 1 SHA-256 hashes.
3. h = HMAC-SHA256(key = seed, message = "SYMBOL:t"), for example "FOH50:1793836800".
4. u1 is the first 6 bytes of h read as a big-endian number, plus 1, divided by 2⁴⁸. u2 is the next 6 bytes divided by 2⁴⁸.
5. z = √(−2 ln u1) × cos(2π u2), a standard normal number.
6. price = previous price × exp(−σ²/2 × dt + σ × √dt × z), rounded to 2 decimals, where dt = 1 / 31,536,000 and σ is the index's volatility below. The first tick of the chain starts from 10000.

How payouts are set

Your payout is your stake divided by the chance of winning plus our margin:

payout = stake ÷ (probability + margin)

The probability comes from the same model that makes the prices, so it's the real chance of winning. The margin is currently …. It's the same for everyone and is the only edge we take. You see the payout before you buy.

Check a day yourself

Pick an index and a finished day. Your browser takes that day's published seed, checks that it hashes into the chain, recomputes every price for the day using the method above, and compares them with the one-minute candles we served. Nothing is sent back to us.

Published seeds

Each day's seed is published once the day is over (UTC). Today's stays secret until midnight. The last 90 days are listed. Hashing any seed gives the one for the day before it.

Practice Simulator

The Practice Simulator is different. It can only be traded with your Demo balance and never settles Real money. We set how it behaves to help you practise (for example calm, trending or jumpy), and its name in the market list shows the current setting. Its prices aren't committed in advance, and practice results don't predict results on any other market.