S&P 500 (SPX) Up or Down on July 20?

Platform comparison

Market context

The real-world event this market tracks is whether the S&P 500 closed higher or lower on Monday, 20 July 2026 compared to the previous trading day. In prediction markets, a YES share pays out if the index rises, while a NO share pays out if it falls; buying either is a wager on that specific daily outcome. This market resolves to "Up" only if the official closing price on 20 July exceeds the prior day’s close, and to "Down" if it is lower.

Historical daily moves in the S&P 500 are typically small, with most trading days ending within ±1% of the prior close. A 0% crowd-implied probability for "Up" is extreme and suggests the crowd believes a decline is virtually certain, yet such certainty is rare in equity markets absent a major shock. Comparable cases show that even during downturns, daily gains still occur roughly 45–50% of trading days, making a 0% probability an outlier that may reflect overconfidence or a data error rather than a true consensus.

Traders should watch the prior day’s economic calendar, especially inflation prints, Fed commentary, and earnings from mega-cap tech firms, which often drive short-term SPX direction. On 20 July 2026, softer-than-expected global inflation data initially lifted the index to a record high of 5,847.32, up 0.87%, before sentiment shifted later in the week amid AI chip selloffs and geopolitical tensions [1][2]. The key dependency is whether the market’s optimism on rate cuts starting in September sustains or reverses by Monday’s close [1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Prediction Market UK, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Prediction Market UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Prediction Market UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.