Largest IPO by market cap in 2026?

Platform comparison

Active sub-markets

Market context

A share in this market is a claim on which 2026 IPO will finish its first trading day with the **largest market capitalisation** in US dollars, using the official closing price and the company’s outstanding shares. In prediction-market terms, a **YES** share pays out if the named company wins that comparison; a **NO** share loses if it does not, so the key question is not the size of the offer itself but the value the stock market assigns at the first close.[1][4]

The historical frame matters because the biggest IPOs by money raised are not always the biggest by market cap on day one. Alibaba’s 2014 US debut long set the benchmark for a large offering, while recent coverage has focused on SpaceX’s 2026 float as a potential record-breaker, with reports of a roughly $75 billion target and a listing planned on Nasdaq. That kind of “megacap” flotation is the clearest reason the current probability may concentrate on a small number of very large private companies rather than the average 2026 IPO, of which there have already been dozens this year.[2][3][5][7]

For traders, the main catalysts are filing dates, final pricing, the number of shares sold, and whether the company’s valuation is revised during the roadshow. Any delay, downsizing, or change in insider selling can alter the closing market cap even if the IPO remains large. Market commentary in May pointed to SpaceX as the standout candidate, while broader 2026 IPO coverage also flagged possible offerings from major AI firms such as OpenAI or Anthropic, though their timing may slip beyond 2026.[2][3][5]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Largest IPO by market cap in 2026? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Prediction Market UK, 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.

What does it cost to trade on Prediction Market UK?

Zero. Prediction Market UK routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.