S&P 500 (SPX) Opens Up or Down on June 1?

Platform comparison

Market context

The S&P 500 faces a gap-up or gap-down decision at the May 31 close, with the opening bell on June 1 determining whether traders enter the new month with positive or negative momentum. Overnight futures movement, earnings surprises, and macroeconomic data releases between now and market open will shape the directional bias. The current 100% probability assigned to "Up" reflects either extreme confidence in bullish positioning or a technical artefact of low liquidity in this particular market; historically, opening gaps occur in both directions with meaningful frequency, making such certainty unusual for a directional binary.

Historical data on S&P 500 opening gaps shows roughly 45–55% split between up and down opens across typical trading periods, though the distribution shifts during earnings season, Fed announcements, or geopolitical events. The May jobs report (if released before June 1) and any late-month inflation signals could trigger overnight positioning shifts that materialise at the open. Treasury yield movements, oil price action, and European market closes on May 31 will feed into US equity futures pricing overnight.

Traders should monitor the final week of May for any surprise economic data, corporate guidance revisions, or shifts in rate expectations. The settlement window closes at 20:00 GMT on June 1, giving markets the full US trading session to establish the official open price against the prior close. Any major overnight news—geopolitical developments, central bank communications, or earnings misses—could easily reverse the current probability skew.

Methodology

This page reviews S&P 500 (SPX) Opens Up or Down on June 1? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at Prediction Today — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On Prediction Today, which mirrors the Polymarket order book at 0% fees. 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?

Not under $1,500 of lifetime trading volume. Above that threshold, Prediction Today triggers a quick verification flow that finishes in minutes.

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.