Economic calendar APIs and the delay between release and data
Posted: Sat Oct 31, 2026 7:20 pm
Automated systems often use a calendar API to know when news events occur and to block trading around them. The scheduled times are generally reliable, but the actual data values, if the system uses them, arrive with a delay.
Some APIs update actuals within seconds, others take minutes. Rate limits, caching, and polling intervals add further lags. A system that depends on the value to trade will be behind.
For filtering purposes, only the schedule is needed, which is available well in advance. The risk lies in schedule changes: events are sometimes rescheduled, added, or removed. Pulling the calendar once a week might miss changes. Refresh it daily, and again before the session.
Handle time zones carefully. The API may provide times in a specific zone or in UTC. Verify against known events.
Also build a fallback. If the API is unavailable, the system should either use a cached schedule or stop trading around standard release times.
The reliability of the filter depends on the reliability of the data source.
How often is the calendar refreshed, and what happens if the source is unreachable?
Some APIs update actuals within seconds, others take minutes. Rate limits, caching, and polling intervals add further lags. A system that depends on the value to trade will be behind.
For filtering purposes, only the schedule is needed, which is available well in advance. The risk lies in schedule changes: events are sometimes rescheduled, added, or removed. Pulling the calendar once a week might miss changes. Refresh it daily, and again before the session.
Handle time zones carefully. The API may provide times in a specific zone or in UTC. Verify against known events.
Also build a fallback. If the API is unavailable, the system should either use a cached schedule or stop trading around standard release times.
The reliability of the filter depends on the reliability of the data source.
How often is the calendar refreshed, and what happens if the source is unreachable?