Arbitrage
Combine opposite outcomes when their total cost is below the resolution payout
Arbitrage buys the same number of shares in two complementary outcomes. If the combined cost—including estimated fees—is below $1.00 per pair, the position can return more than it cost when held through resolution.
Core condition
Outcome A price + Outcome B price + estimated fees must be below $1.00 per matched pair.
Available strategies
| Strategy | First leg | Opposite leg | Balance requirement |
|---|---|---|---|
| Outcome | Dreamsea | Same Dreamsea market | One Dreamsea balance funds both legs |
| Polymarket | Dreamsea | Matching Polymarket market | Each platform funds its own leg |
Outcome labels do not need to be Yes and No. They can be Up/Down or two opposing teams, as long as the outcomes are complementary and exactly one pays $1.00 at resolution.
The Polymarket strategy appears only when it is enabled and the market has a compatible mirror.
Example
Suppose the order books can fill 100 matched pairs at:
| Leg | Price | Shares | Cost |
|---|---|---|---|
| Outcome A | $0.42 | 100 | $42.00 |
| Outcome B | $0.53 | 100 | $53.00 |
| Estimated fees | $1.00 | ||
| Total cost | $96.00 | ||
| Resolution payout | $100.00 | ||
| Estimated profit | $4.00 |
The calculation is:
matched shares × ($1.00 − combined price − fees per pair)
100 × ($1.00 − $0.95 − $0.01) = $4.00Whichever outcome wins, 100 winning shares redeem for $100 and the other 100 shares redeem for $0.
This example is illustrative. Use the live quote: it accounts for order-book depth, fees, balances, minimum sizes, and the quantity both legs can fill.
Place an arbitrage order
Open Arbitrage
Select Arbitrage in the order panel, then choose Outcome or Polymarket.
Review both legs
Confirm the outcome, platform, executable price, estimated fees, and expected return for each leg.
Choose matched size
Enter an amount or use Min, Mid, or Max. The maximum is limited by profitable liquidity and the balance required for both legs.
Sign both orders
Each leg requires a signature. Outcome arbitrage sends both orders to the Dreamsea CLOB; Polymarket arbitrage sends one to each platform.
Verify the result
Check both reported statuses and your positions before submitting another order.
Execution risks
The two orders are not one atomic transaction. Although each leg uses fill-or-kill execution, one leg can fill while the other fails. This creates temporary directional exposure.
Before signing, confirm:
- both platforms have enough balance;
- the quoted quantities are equal;
- the markets use compatible resolution criteria;
- expected profit remains positive after fees;
- you can monitor and correct a partial result.
Resolution criteria must match
Similar market titles do not guarantee identical outcomes. Compare the rules, dates, sources, and edge cases on both platforms before using cross-platform arbitrage.
Common questions
Why is Max lower than my balance?
Max is limited by the smaller of the two balances, the profitable liquidity shared by both legs, minimum order rules, and exchange quantity rounding.
Can I exit before resolution?
Yes, but the displayed arbitrage return assumes equal opposite positions are held through resolution. Selling early creates new trades at current prices and changes the result.
What should I do if only one leg fills?
Review the completed leg and current order books before acting. Depending on price and liquidity, you can retry the missing leg, reduce the filled position, or keep the exposure.