Resolution criteria on PolyGram: This market will resolve according to the party of the candidate who wins the CA-18 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 4, 2026. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources.
PolyGram is an on-chain prediction market where you trade YES or NO outcome shares with real USDC on Polygon. For this market, buy YES if you believe the event will happen, or NO if you think it won't. Your maximum loss is your stake — winning shares pay $1.00 each at resolution. Unlike sportsbooks, there is no house edge: prices are set by supply and demand from other traders and reflect the crowd's real-time probability.
Market outcomes
| Democratic Party | 95% YES | 5% NO |
| A | — | |
| C | — | |
| E | — | |
| Republican Party | 4% YES | 96% NO |
| Other | — | |
| B | — | |
| D | — | |
California's 18th congressional district will elect a representative to the U.S. House in the 2026 midterm elections on 4 November. The current order book on Polymarket reflects a 94% implied probability for a Democratic victory, suggesting the market views this seat as solidly Democratic territory. The settlement will depend on which party's candidate receives the most votes, with affiliation determined by ballot listing or identifiable party association at the time results are conclusively called.
CA-18 has voted Democratic in recent cycles, though the district's composition and electoral dynamics merit examination against comparable suburban and semi-rural California seats. The 2022 midterms saw Democrats perform better than historical expectations in House races nationwide, whilst California specifically bucked the typical midterm pattern. Historical precedent suggests districts with strong Democratic registration advantages and recent Democratic performance tend to remain in Democratic hands, though redistricting changes and candidate quality can shift outcomes materially.
Traders should monitor candidate announcements and primary results as they emerge through 2025 and into 2026, which will clarify field strength and potential recruitment successes. Broader political conditions—including presidential approval ratings and economic indicators heading into the election—will likely influence the district's competitive posture. Any significant demographic shifts or redistricting adjustments affecting CA-18's boundaries could alter the underlying fundamentals supporting the current probability assessment.
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a two-hour dispute window opens, and if no one stakes a counter-claim the payout is final. Contested outcomes escalate to UMA token-holder voting. Payouts clear in USDC to the winning side.
The mechanics for trading "CA-18 House Election Winner" are the same as any other PolyGram event contract. Each YES share resolves to $1 if the event happens, or $0 if it doesn't. The current price between 0¢ and 100¢ is the market's probability estimate, set live by the order book.
$34K in lifetime turnover and $22K of resting liquidity puts this market in the around the median by volume for elections contracts on PolyGram. Order-book depth is modest — expect a couple of cents of slippage on $1k+ trades.
Last 24 hours alone saw $2K in turnover, consistent with the market's lifetime daily-average pace.
The market has been open for 3 months — the price has had time to stabilise as new information arrived.
Higher-volume markets tend to have tighter spreads and faster price discovery — meaning the displayed YES/NO percentages are more likely to reflect the true crowd-implied probability rather than a single trader's directional view.
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a 2-hour dispute window opens, and if uncontested the payout is final. Contested outcomes escalate to UMA token holders.
This prediction market is scheduled to close on 3 November 2026. After the resolving event occurs, settlement typically clears within 24 hours once the UMA optimistic oracle confirms the outcome. All payouts are in USDC on the Polygon network.
To trade on this prediction market, create a free PolyGram account at polygram.ink, deposit USDC via Polygon, and place a YES or NO order on the outcome you believe in. You can learn more on our how-it-works page. Your maximum loss is limited to your stake — there is no leverage or margin.
When the outcome is determined, winning YES shares pay out $1.00 each in USDC, while losing shares pay $0. Settlement is handled by the UMA optimistic oracle on Polygon — a proposer submits the result, a two-hour dispute window opens, and if uncontested, payouts are distributed automatically. You can withdraw your winnings to any Polygon wallet.
Prediction-market positions can lose 100% of staked capital. Outcomes are uncertain by definition — historical accuracy of crowd-implied probabilities is high in aggregate but not for any single market. PolyGram does not provide investment advice. Trade only with capital you can afford to lose.
Regulatory status varies by jurisdiction. Germany, the United States, and most EU countries treat Polymarket-style event contracts under one of three frameworks: financial derivative, gambling product, or unregulated novel asset. Consult local counsel before trading.
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