Largest IPO by market cap in 2026?

Platform comparison

Market context

Polymarket is pricing this contract at **92% YES**, with the orderbook heavily tilted towards a single mega-listing dominating the 2026 field. On Polymarket, the position is held in **USDC** on **Polygon**, with outcome exposure represented through conditional tokens, so traders are effectively betting on which first-day listing will finish with the highest official closing market capitalisation in dollar terms.

The pricing makes sense against recent comparables. Fervo Energy’s May 2026 debut was described as the largest clean energy IPO ever, raising $1.89bn and closing its first day at a market value above $10bn, but that scale still sits far below the mega-cap private names usually discussed for a 2026 listing.[6][7] The market’s candidate list on Preddy is dominated by SpaceX, which the same venue prices around 86%, while Anthropic, OpenAI and others sit much lower; Octagon’s climate-science market view also has SpaceX around 91% and says there is no strong sign of mispricing.[2][3]

For traders, the key catalysts are concrete filing and timing signals rather than broad IPO sentiment. Watch for S-1 or F-1 registration statements, underwriter appointments, lock-up and share-count disclosures, and any board-approved listing timetable, because this market resolves on the company’s *first-trading-day* closing market cap, not on proceeds raised.[2] Bloomberg reported on 13 July that the AI power boom had sparked a record rush into climate-tech deals, while TechCrunch said in April that the climate-tech IPO window could be cracking open, both pointing to a busier pipeline even if only one name ultimately reaches the tape first.[8][14]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Largest IPO by market cap in 2026? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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 PolyGram. 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%.