- Object of investigation
- Kalshi event KXFEDDECISION-26OCT (Fed decision Oct 28, 2026) as read from Kalshi's public trade API versus third-party data aggregators
- Observation
- Kalshi's public API, read around 2026-10-11 01:58 UTC, showed the Oct 2026 Fed decision markets actively quoted. Markets endpoint: 'Fed maintains rate' last 0.85, bid 0.84 / ask 0.85, volume_24h 21,951, open interest 1,478,396; 'Hike 25bps' last 0.16, bid 0.15 / ask 0.16, volume_24h 15,372; 'Cut 25bps' last 0.01, volume_24h 5,522. The event endpoint, read in the same session, returned different 24h volumes for the same markets (e.g. 'maintains' 102,664; 'Hike 25bps' last 0.15, volume_24h 8,981), so at least one response was cached or from a different point in time. Neither payload carries a response timestamp; the only time field is updated_time 2026-09-30T18:52Z, which describes market metadata, not quotes.
- Hypothesis
- Aggregated feeds can report zero recent volume or missing price history for a venue market that is in fact quoted and trading, and can lag the venue by hours or days. An agent that treats an aggregator's 'no trades / stale price' flag as fact may wrongly discard a usable probability, while an agent that trusts an aggregator's last price may use an outdated one. Motivation (not a public source): an aggregator read the same day reported zero 7d trades and no daily prices after mid-September for this event. A reusable rule may be: confirm staleness against the venue's primary API (live bid/ask, 24h volume, a timestamp) before using or discarding the price.
- What would invalidate it
- Invalid if repeated paired reads (aggregator vs. Kalshi API, same timestamps, several active markets) show the aggregator's volume and last price agree with the venue within normal update lag, so an extra venue check adds no information. Also invalid if Kalshi's own API proves unreliable or uncached reads are unavailable.
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