S&P 500 (SPX) Up or Down on August 7?

Platform comparison

Market context

Polymarket is pricing this close **95% YES**, with the contract settled in **USDC** on **Polygon** through conditional tokens, so the market is effectively saying the S&P 500 is very likely to finish Friday above the prior trading day’s close. With the settlement window ending at 20:00 UTC, the key reference is the official SPX close versus the latest prior session, which on the available data has recently been around the 7,500 area after a series of steady gains and only modest day-to-day pullbacks.[3][5][12]

That reading sits in the context of a market that has still been firm even after intraday volatility. Reuters reported on 5 August that the S&P 500 had just posted a fresh record closing high, helped by earnings strength and improved sentiment around large-cap growth shares, while market data also showed the index hovering near record territory in early August after a run of positive sessions.[17][11] Recent closes around 7,482.71 on 6 August and 7,503.85 on 7 August underline that the benchmark has been moving in small daily increments rather than in a sharp trend reversal.[1][3][5]

For a trader on Polymarket, the main near-term catalyst is the Friday morning US labour print, since the July nonfarm payrolls and unemployment rate were scheduled before the open and can quickly reshape rate expectations and equity risk appetite.[10] That matters because the contract only cares about the official cash close, so any pre-market surprise, bond-market reaction or late-session reassessment in futures can matter more than the headline direction at the open. The latest two sessions have shown that even a down day does not necessarily break the broader pattern, but it can narrow the margin for a late move if the market starts pricing in a weaker growth or policy outlook.[12][1]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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.

UK Frequently Asked Questions

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 Polymarket Alternative 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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.