Polymarket trading API outage delays unfilled order data, suspends trading
Polymarket's trading API suffered a major outage on August 31 that delayed responses when users read unfilled orders on its central limit order book. The platform suspended trading entirely in response to the incident. At 9:45 a.m. UTC, Polymarket targeted a 10:00 a.m. UTC restoration and said it would provide an updated ETA as available. The cause of the malfunction and whether open positions were impacted remained unconfirmed.
This marks Polymarket's second trading halt in under a week, after a prior outage five days ago that also degraded API performance. The repeat timing matters because the platform is courting institutional API users and market makers whose strategies depend on reliable order book access. Bot-driven liquidity already dominates Polymarket, and automated systems abort positions at the first sign of downtime.
Each incident pushes those operators to test Kalshi or Novig as backup venues. The CFTC does not publish uptime grades, but operational risk is a live examination topic for designated contract markets. Polymarket cannot scale U.S. parlays or prime API access until it hardens its stack against repeat failures.