S&P 500 (SPX) Up or Down on August 5?

Platform comparison

Market context

The S&P 500 is being priced as a **heavy favourite to finish up**, with the market currently implying **0% for a YES “Up” result** even though the index has just been printing fresh highs and holding above the June peak. That makes the consensus side overwhelmingly one-way, and any trader looking for value would have to lean against a very strong momentum tape rather than follow it.

The recent frame is straightforward: the index closed at **7,736.52** on Tuesday after a **1.8%** jump and a new all-time closing high, while the Dow and Nasdaq also finished sharply higher[1]. That follows a strong late-summer run, with the S&P 500 also up **2.3%** for the week in comparable recent trading data[3]. On that backdrop, the favourite is still **Up**, but the quoted probability suggests the crowd has either overcorrected towards a binary “down day” view or is waiting for a catalyst-heavy session to fade the rally.

For catalysts, traders are watching whether the record-setting move can survive the next round of macro and earnings headlines. Recent coverage pointed to a rotation out of technology at the open, higher bond yields, and a July jobs report due on Friday as the next major macro test, with Fed-cut expectations still in play[4]. CNBC also noted technicians want consecutive closes above **7,620** to confirm the breakout, which matters because today’s close is the settlement print for this market[19]. That leaves the contrarian angle on **Down** tied to any late-session reversal in megacap tech, rates, or energy, while the consensus case remains that momentum and record-high sentiment should keep the index above yesterday’s close[1][19].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track S&P 500 (SPX) Up or Down on August 5? 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

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.

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 Who Will Win. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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%.