diff --git a/migrations_lockfile.txt b/migrations_lockfile.txt
index 2d03a269bd5daf..9e9f6cb59f86fc 100644
--- a/migrations_lockfile.txt
+++ b/migrations_lockfile.txt
@@ -27,7 +27,7 @@ preprod: 0014_commitcomparisons_fk
 
 replays: 0006_add_bulk_delete_job
 
-sentry: 0965_gzippeddict_big_tables
+sentry: 0966_groupopenperiod_data_pending_inc_detector_id_index
 
 social_auth: 0003_social_auth_json_field
 
diff --git a/src/sentry/migrations/0966_groupopenperiod_data_pending_inc_detector_id_index.py b/src/sentry/migrations/0966_groupopenperiod_data_pending_inc_detector_id_index.py
new file mode 100644
index 00000000000000..1decad68a2d9cc
--- /dev/null
+++ b/src/sentry/migrations/0966_groupopenperiod_data_pending_inc_detector_id_index.py
@@ -0,0 +1,35 @@
+# Generated by Django 5.2.1 on 2025-08-08 23:06
+
+from django.db import migrations, models
+
+from sentry.new_migrations.migrations import CheckedMigration
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production.
+    # This should only be used for operations where it's safe to run the migration after your
+    # code has deployed. So this should not be used for most operations that alter the schema
+    # of a table.
+    # Here are some things that make sense to mark as post deployment:
+    # - Large data migrations. Typically we want these to be run manually so that they can be
+    #   monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   run this outside deployments so that we don't block them. Note that while adding an index
+    #   is a schema change, it's completely safe to run the operation after the code has deployed.
+    # Once deployed, run these manually via: https://develop.sentry.dev/database-migrations/#migration-deployment
+
+    is_post_deployment = True
+
+    dependencies = [
+        ("sentry", "0965_gzippeddict_big_tables"),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name="groupopenperiod",
+            index=models.Index(
+                models.F("data__pending_incident_detector_id"),
+                name="data__pend_inc_detector_id_idx",
+            ),
+        ),
+    ]
diff --git a/src/sentry/models/groupopenperiod.py b/src/sentry/models/groupopenperiod.py
index d5d7adef14cd1e..f3a89033183d6e 100644
--- a/src/sentry/models/groupopenperiod.py
+++ b/src/sentry/models/groupopenperiod.py
@@ -73,6 +73,10 @@ class Meta:
         indexes = (
             # get all open periods since a certain date
             models.Index(fields=("group", "date_started")),
+            models.Index(
+                models.F("data__pending_incident_detector_id"),
+                name="data__pend_inc_detector_id_idx",
+            ),
         )
 
         constraints = (