Bitcoin Up or Down: 5-minute and 15-minute BTC prediction rounds on Arc

By the arky team · Last updated: 5 Oct 2026

Exactly how arky's Up/Down rounds work: the pot, the price source, the void rules, the 11 pairs and how to place a bet, with an honest note on risk.

How does Bitcoin Up or Down work?

Each Bitcoin Up or Down round asks one question: will BTC's price at the close of the round be higher or lower than at its start? Rounds run back to back on a fixed grid, every 5 minutes or every 15 minutes, and the close of one round is the start (the "lock") of the next.

• Lock price. The strike is a 60-second time-weighted average price (TWAP) of RedStone signed price data, ending at the lock time: six points, 10 seconds apart.
• Close price. The same 60-second TWAP, ending at the close time.
• Outcome. Up wins if the close is above the lock, Down wins if it is below. Only an exact tie is a push.
• Betting window. Bets on a round close about a minute before it locks, because the strike averages the last 60 seconds. You can also bet on upcoming rounds up to about an hour ahead.

How is the payout calculated?

Bitcoin Up or Down on arky is pari-mutuel: every bet on a round goes into one pot, and when the round settles the winning side shares the pot in proportion to stake. Your payout is your stake × (pot − fee) ÷ the total staked on the winning side.

An illustrative example, ignoring the fee: a round ends with 300 USDC on Up and 700 USDC on Down, a 1,000 USDC pot. BTC closes higher. A 100 USDC Up bet receives 100 × 1,000 ÷ 300 ≈ 333 USDC. A Down bet receives nothing. Because the pot is shared, your implied odds keep moving until betting closes, and the popular side pays less.

arky takes a small fee from the pot of settled rounds. The fee can never be larger than the losing side, so a winner never gets back less than their stake. Void rounds pay no fee.

When is a round void and refunded?

A round is void, and every bet is refunded in full with no fee, in four cases:

• Exact tie. The close price equals the lock price.
• One-sided round. Everyone bet the same way, so there is no one to pay the winners. This is known at the lock, before any result.
• No price. No valid RedStone price is posted within 2 hours of the close.
• Mixed sources. The lock and close prices came through different versions of the price verifier, which can only happen during a scheduled source change.

None of these can be triggered by a losing bettor after the result is known: anyone can post the RedStone price, and a stored price can never be replaced.

Which coins can you bet Up or Down on?

arky runs 5-minute and 15-minute Up/Down rounds on 11 pairs: BTC, ETH, SOL, XRP, BNB, DOGE, ADA, AVAX, AAVE, POL and TRX. That is 22 round series in total, all in USDC on Arc. Ethereum Up or Down, Solana Up or Down and XRP Up or Down work exactly like Bitcoin Up or Down. For leveraged positions on the same majors, see crypto perps on Arc.

How to bet on Bitcoin Up or Down on arky

1. Open app.arky.bet and connect a wallet. Onboarding walks you through it.
2. Deposit USDC to Arc with the Deposit wizard (Circle CCTP). You need no ETH: USDC pays gas on Arc.
3. Open the Up/Down rounds and choose BTC and a 5-minute or 15-minute round.
4. Pick Up or Down and enter an amount in USDC (minimum 1 USDC).
5. Sign the bet with your wallet before betting on that round closes.
6. After the round settles, claim your winnings or your refund to your wallet.

Bitcoin Up or Down on arky vs Polymarket and Kalshi

All three offer short bitcoin rounds, but they are built differently (as of October 2026):

Sources: Polymarket changelog, a Polymarket 5-minute market's rules, PredictionMarketsPicks on Kalshi; arky from the ArkyUpDown contract. Checked 5 Oct 2026.

For a wider view of the venues, read crypto prediction markets compared or arky vs Polymarket.

Is there a winning strategy for Bitcoin Up or Down?

No strategy wins reliably. Over 5 or 15 minutes, bitcoin's moves are mostly noise, and the fee on settled rounds means the average bettor loses a little over time. What you can control is how you play:

• Check the pot split before betting closes: the crowded side pays less.
• Remember the strike is a 60-second average, not the last tick on a chart.
• Set a budget per session and stop when it is gone. Do not chase losses.

Play responsibly. Up/Down rounds are high-risk and you can lose your whole stake on every round. Nothing on this page is financial advice. Rules for prediction markets differ by country; check your local rules and the arky terms first.

How are rounds settled, and can arky change the result?

Rounds settle on chain from RedStone price data, and arky holds no key that can set a price. Prices are posted by anyone from RedStone's signed packages, checked by an on-chain verifier against RedStone's signers, and stored once: a stored price can never be rewritten. Pausing a series only stops new bets; it never blocks settlement, claims or refunds, and no owner function moves user funds. You can read the contract on the Arc explorer and learn more about the oracle in the RedStone docs. Arc itself is described in the Arc docs and in what is Arc.