Largest IPO by market cap in 2026?

Platform comparison

Active sub-markets

Market context

The event is the first-day public market valuation of any company that completes an IPO in 2026, measured by official closing price multiplied by outstanding shares. In practice, that means the outcome will be driven less by the offer size alone than by how the stock is priced and traded on debut, which can produce a different ranking from “largest amount raised” or “most valuable private company” narratives.

The main comparison point is the recent SpaceX listing, which CNBC said was positioned as the biggest IPO in history, with reports of a roughly $75 billion raise and a Nasdaq debut expected to set a new record[1]. Forbes also framed SpaceX as a blockbuster offering and noted a June 12 debut at a nearly $2 trillion valuation, underscoring how a single megacap listing can dominate this kind of market if it is the only truly scale IPO in the window[2]. MSCI has separately warned that potential megacap IPOs in 2026 could reshape benchmarks, which is the relevant backdrop for reading any implied probability here: the field may be concentrated, but the ranking is still sensitive to issuance terms and first-day pricing[3].

For traders, the key catalysts are official prospectuses, IPO calendars, and any updates on valuation ranges, share counts, or listing venue, because the market resolves from the first trading day close rather than later aftermarket performance. Reuters-style deal coverage is the most useful type of input when available, especially for confirming whether a planned float survives regulatory review and market conditions. Accessibility is also shaped by platform and jurisdiction: German GlüStV rules can affect whether a resident may access a prediction market at all, US CFTC reach matters if the venue is deemed to touch US derivatives regulation, and “no-KYC up to $1,500” usually means smaller participation can be opened with limited identity checks, but only within the operator’s own policy and subject to local restrictions.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket KYC UK, which mirrors the Polymarket order book directly.

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.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket KYC 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.

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 it cost to trade on Polymarket KYC UK?

Zero. Polymarket KYC 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 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.