Trade: S&P 500 (SPX) Opens Up or Down on May 14?
Resolution criteria on PolyGram: This market will resolve to "Up" if the official S&P 500 Index open price for S&P 500 (SPX) on May 14 is higher than the official S&P 500 Index closing price for SPX on the most recent prior trading day. This market will resolve to "Down" if the official S&P 500 Index open price for S&P 500 (SPX) on May 14 is lower than the official S&P 500 Index closing price for SPX on the most recent prior trading day. E.g., ordinarily, a market on Monday would refer to the previous Friday for its most recent closing price, unless that Friday were a market holiday, in which case it would refer to Thursday, or the next most recent trading day.
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.
- Liquidity
- $3K
- Total Volume
- $2K
- 24h Volume
- $2K
- Open Interest
- $1K
Market outcomes
| S&P 500 (SPX) Opens Up or Down on May 14? | 69% YES | 32% NO |
Market context
On 14 May 2026, traders are pricing the probability that the S&P 500 opens above its prior close at 65% on Polymarket's order book. This is a directional gap bet—whether overnight sentiment and pre-market activity push the index higher at the opening bell relative to the previous trading day's close. The current implied probability reflects positioning ahead of what will likely be a routine market open, absent significant overnight developments or pre-market news flow.
Historical data on S&P 500 opening gaps shows roughly 52–55% of trading days open higher than the prior close under normal conditions, though this varies materially with market regime. During periods of elevated volatility or ahead of major economic data releases, gap-up probabilities can shift substantially. The 65% implied probability currently priced suggests traders are positioning for a modestly bullish overnight sentiment, above the long-run baseline. This could reflect recent market momentum, positioning in index futures overnight, or anticipated positive catalysts.
Traders should monitor overnight developments in Asian and European equity markets, any after-hours earnings announcements, and the economic calendar for 14 May itself. Depending on what data or corporate news emerges between the prior close and market open—particularly around inflation figures, earnings surprises, or geopolitical developments—the gap probability could shift materially. Futures trading and sentiment in overnight sessions will be the primary driver of actual opening direction, making pre-market price action the key variable to watch as settlement approaches.
Wikipedia Context
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S&P 500S&P 500 is a stock market index tracking the stock performance of 500 leading companies listed on stock exchanges in the United States. It is one of the most commonly followed equity indices and includes approximately 80% of the total market capitalization of U.S. public companies, with an aggregate market cap of more than $61.1 trillion as of December 31, 2
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S&P 500 Dividend Aristocrats
The S&P 500 Dividend Aristocrats is a stock market index composed of the companies in the S&P 500 index that have increased their dividends in each of the past 25 consecutive years. It was launched in May 2005.
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S&P 500 futures
S&P 500 Futures are financial futures which allow an investor to hedge with or speculate on the future value of various components of the S&P 500 Index market index. S&P 500 futures contracts were first introduced by the Chicago Mercantile Exchange in 1982. The CME added the e-mini option in 1997. The bundle of stocks in the S&P 500 is, per the name, compose
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List of S&P 500 companiesThe S&P 500 is a stock market index maintained by S&P Dow Jones Indices. It comprises 503 common stocks which are issued by 500 large-cap companies traded on American stock exchanges. The index includes about 80 percent of the American market by capitalization. It is weighted by free-float market capitalization, so more valuable companies account for relativ
Resolution source
This market settles from the official outcome published at https://www.wsj.com/market-data/stocks. A proposer submits the final result to the UMA optimistic oracle on Polygon; the two-hour dispute window closes and payouts clear in USDC.
How to trade this market step by step
The mechanics for trading "S&P 500 (SPX) Opens Up or Down on May 14?" 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.
- Sign in on polygram.ink with your email — no full KYC under $1,500 lifetime trading volume.
- Deposit USDC on Polygon (lowest fees, ~$0.01 per transaction) or Ethereum. Funds credit after 12 confirmations.
- Pick a side. Buy YES if you believe the event will happen; buy NO if you think it won't. The current YES price reflects the market's collective probability.
- Size your position. If you stake 100 USDC at 69% YES, you'll receive shares that pay $145 if YES resolves true — a 45% gross return. If NO resolves, your shares are worth $0.
- Set risk controls (optional). Stop-loss, take-profit, and limit-order types all supported. Use the trade ticket's slippage box to cap your maximum entry price.
- Wait for resolution. When the event resolves on-chain via the UMA optimistic oracle, the winning side settles to 100¢ automatically and USDC hits your balance within seconds. Withdrawable to any wallet you control.
How active is this market?
$2K in lifetime turnover and $3K of resting liquidity puts this market in the below the median by volume for spx contracts on PolyGram. Order-book depth is thin — large orders may need to be split across the book or executed as limit orders.
Last 24 hours alone saw $2K in turnover, well above the lifetime daily-average for this market — a clear sign of news catalysing trader activity right now.
The market has been open for under a month — fresh enough that information asymmetry remains a real factor.
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.
Key terms
- YES / NO share
- A binary outcome token that pays $1.00 if the underlying claim resolves true (YES) or false (NO), and $0 otherwise. The market price between 0¢ and 100¢ is the implied probability.
- CLOB
- Central limit order book. The matching engine that pairs YES buyers with NO buyers (effectively the same trade). Polymarket's CLOB on Polygon executes trades on-chain via the conditional-tokens framework.
- Liquidity
- USDC capital sitting in resting limit orders inside the order book. Deeper liquidity means smaller slippage on large trades and a tighter bid-ask spread.
- UMA optimistic oracle
- The on-chain dispute system that settles each Polymarket market. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution.
- Slippage
- The difference between the displayed mid-price and your fill price. Affects market orders most; limit orders avoid slippage but may take time to fill.
- Conditional token
- ERC-1155 outcome share issued by Gnosis Conditional Tokens on Polygon. The token type that resolves to $1.00 or $0.00 at settlement.
Frequently asked questions
What is the current probability for "S&P 500 (SPX) Opens Up or Down on May 14?"?
As of today, traders on Polymarket price this outcome at 69%. The number updates continuously as the order book clears. PolyGram mirrors the same live odds with locale-aware formatting and USDC settlement.
How does this market resolve?
Resolution is sourced from https://www.wsj.com/market-data/stocks. Settlement is executed by the UMA optimistic oracle on Polygon, with a 2-hour dispute window before payouts clear.
When does this market close?
This prediction market is scheduled to close on 14 May 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.
How can I trade on "S&P 500 (SPX) Opens Up or Down on May 14?"?
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.
What happens when the market resolves?
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.
Risk and regulatory note
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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