Largest IPO by market cap in 2026?

Platform comparison

Market context

The real-world event driving this market is the anticipated initial public offering of SpaceX, which has confidentially filed for an IPO with a targeted valuation between $1.75 trillion and $2 trillion, potentially making it the largest IPO in history if it lists in June 2026[5]. Unlike smaller offerings, this transaction hinges on the company’s first trading day closing price in U.S. dollars, where market capitalisation equals outstanding shares multiplied by that share price[7].

Historically, megacap IPOs such as those by Alibaba or Visa reshaped global benchmarks by altering market exposures, yet SpaceX’s projected scale dwarfs even those precedents[2]. While 2026 has already seen 79 IPOs with June being the most active month, the market’s current implied probability of 86.5% for SpaceX reflects confidence that no other firm, including Anthropic or OpenAI, will match its valuation[1][4]. Platforms diverge here: Polymarket offers decimal odds without KYC, whereas Kalshi requires identity verification and uses implied probability, creating different liquidity dynamics for this binary outcome.

Traders should monitor SpaceX’s roadshow schedule, regulatory approvals from the SEC, and any pricing announcements expected in the fall, as these dependencies will confirm the listing date[3]. Recent reporting confirms SpaceX’s successful pricing at an $86 billion valuation in a prior round, but the $1.75 trillion target remains the critical catalyst for 2026[3]. iShares notes that AI mega-cap firms are projected to rebound in 2026, yet SpaceX’s confidential filing remains the primary variable for market resolution[4]. Fee structures also vary; Betfair charges no commission on wins, while Smarkets applies a flat fee, influencing where traders place capital on this specific event.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Largest IPO by market cap in 2026? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Robinhood Prediction Markets has a different geo footprint and routes to Polymarket's order book at 0% fees.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.