GPT-5.6 released by 2026?

Platform comparison

Active sub-markets

Market context

OpenAI has not yet officially announced GPT-5.6, despite a backend identifier surfacing in Codex rollout logs and chief scientist Jakub Pachocki confirming a “meaningful improvement” over GPT-5.5. While Polymarket traders have placed over $960,000 in bets assigning an 83–89% probability to a late-June launch window (June 22–28), no system card, API model string, or public release date exists as of mid-June 2026[1][2]. This mirrors the pre-launch pattern of GPT-5.5, which became available in the API the day after its ChatGPT debut, suggesting a staged rollout starting with ChatGPT and Codex before broader API access[1].

Traders should monitor for an official OpenAI announcement, a new system card, or Codex version updates, as these typically coincide with public releases[6]. The six-week flagship cadence—GPT-5.4 in March, GPT-5.5 in April, GPT-5.6 expected in June—supports the late-June window, though conservative estimates point to July if delays occur[2][5]. Polymarket’s implied probability (decimal odds vs. percentage) and fee structure differ notably from Kalshi’s KYC-heavy model and Betfair’s decimal odds, creating divergent risk exposures for this specific market[1][2].

The current 0% YES probability on the settlement window ending 31 July 2026 reflects the absence of official confirmation, not a lack of development activity. With the backend identifier confirmed and insider benchmarks suggesting GPT-5.6 outperforms Anthropic Mythos on agentic coding tasks, the market remains highly sensitive to the next official signal[2][6].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares GPT-5.6 released by 2026? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to Kalshi Alternative UK, 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

Where can I trade this market with the lowest fees?

On Kalshi Alternative 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.

Is this market available outside the US?

Kalshi Alternative UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Kalshi Alternative UK triggers a quick verification flow that finishes in minutes.