Investigating Issue with Double Executions

Incident Report for Alpaca

Postmortem

On May 21, 2026, our platform experienced an issue where a subset of overnight fractional limit orders received duplicate executions. The issue affected orders placed between 8:00 PM ET on May 20, 2026 and approximately 8:58 AM ET on May 21, 2026. All affected orders were identified and corrected.

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Our engineering teams monitored the platform overnight process. The incident is now closed.

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We know reliable order execution is critical to your operations, and we thank you for your understanding as we restored services.

Posted May 22, 2026 - 16:03 EDT

Resolved

All duplicate orders have been sorted and we are seeing accounts are restored to normal. We will consider this issue as resolved. Thank you for your patience and understanding.

Posted May 21, 2026 - 16:36 EDT

Update

We are continuing to monitor to ensure the issue is resolved. We greatly appreciate your patience.

Posted May 21, 2026 - 16:30 EDT

Update

Our team team has implemented a fix and we are monitoring to ensure services are restored. We will continue to update you as we monitor. Thank you for your patience.

Posted May 21, 2026 - 15:39 EDT

Update

Our team is continuing to work on resolving this as quickly as possible. We will continue to update you as we progress. Thank you for your patience.

Posted May 21, 2026 - 15:15 EDT

Monitoring

We anticipate a fix to be complete shortly. We will continue to update you as we progress.

Posted May 21, 2026 - 14:57 EDT

Update

Our team is actively working on a fix for buying power and resolving duplicate orders as a high priority. We will continue to update you as we work towards a resolution. We greatly appreciate your patience.

Posted May 21, 2026 - 14:41 EDT

Update

Posted May 21, 2026 - 14:27 EDT

Update

Our team is actively working on a fix for buying power and resolving duplicate orders as a high priority. We will continue to update you as we work towards a resolution.

Posted May 21, 2026 - 14:17 EDT

Update

We have identified the issue which affected buying power. Our team is actively working on a fix for buying power and resolving duplicate orders as a high priority. We will continue to update you as we investigate.

Posted May 21, 2026 - 14:06 EDT

Update

Posted May 21, 2026 - 13:53 EDT

Identified

Posted May 21, 2026 - 13:43 EDT

Update

We are continuing to investigate the buying power issue affecting accounts impacted by the earlier duplicate execution. Our team is actively working on a fix as a high priority. We will continue to update you as we investigate.

Posted May 21, 2026 - 13:25 EDT

Investigating

Posted May 21, 2026 - 13:15 EDT

Update

We have identified a buying power issue affecting accounts impacted by the earlier duplicate execution. Our team is actively working on a fix as a high priority. We will update you once resolved.

Posted May 21, 2026 - 13:04 EDT

Update

Our team is continuing to work on the resolution. We will provide another update once the corrected trade events have been sent.

Posted May 21, 2026 - 12:44 EDT

Update

We are now preparing to send the corrected trade events and will confirm once they have been processed.

Posted May 21, 2026 - 11:46 EDT

Monitoring

We have completed our corrections and the accurate filled quantities should now be reflected in customer accounts. Our teams are now finalising any outstanding data clean up and will provide a formal trade event notification and final update once this is completed.

Posted May 21, 2026 - 11:22 EDT

Identified

All affected orders have been identified. Corrections are in progress and we will confirm once fully resolved.

Posted May 21, 2026 - 10:40 EDT

Investigating

We are currently investigating a technical issue that caused some orders to receive duplicate executions following a restart of the principal engine. This may result in some customers temporarily seeing incorrect filled quantities or affected buying power. Our engineering team is actively working to resolve this We will provide an update once the corrections are complete.

Posted May 21, 2026 - 10:33 EDT

This incident affected: Live Trading API (Orders API) and Broker API (broker.trading.accounts.account_id.orders.get).