S&P 500 (SPX) Up or Down on August 3?

Platform comparison

Market context

Polymarket is pricing this contract at **100% YES**, which implies the crowd sees the S&P 500 as almost certain to close above the previous trading day’s level for Monday’s official cash close. In practice, the settlement is tied to the published S&P 500 Index close, not to intraday futures, and the market settles via Polymarket’s on-chain structure on **Polygon** with **USDC** collateral and conditional tokens determining the payout.

The comparison set matters because this is a one-day direction call on a very large index, not a forecast of trend over a week or month. The S&P 500 ended the prior session at **7,489.72**, after rising **0.7%** on Friday, following a volatile but broadly positive finish to the week; that leaves the contract dependent on whether Monday’s close can beat that benchmark rather than on whether the index is simply “strong” in absolute terms.[1][5] Historical snapshots in the supplied data show the index has moved sharply across recent sessions, with a **1.66%** gain on 30 July and a **1.52%** drop on 29 July, which is the sort of day-to-day swing that usually frames these up-or-down markets.[5]

For traders, the immediate watchlist is the August 3 U.S. calendar: **final S&P Global manufacturing PMI at 10:00 a.m.** and the market’s reaction to any fresh read-through on growth or pricing pressure.[7] Zacks said Friday’s rally was supported by strong AI-linked earnings and a firmer consumer-data print, while MarketWatch noted the broad market was also reacting to lower oil prices and Treasury yields as geopolitical risks eased.[1][2] With the market already closed at 6 p.m. UTC, the remaining information flow is limited, so late-session futures positioning and any after-hours news are more likely to matter than scheduled daytime data for this particular close.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track S&P 500 (SPX) Up or Down on August 3? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.

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.