diff --git a/h/services/bulk_api/lms_stats.py b/h/services/bulk_api/lms_stats.py
index 73cfa059f51..5966a1f0e06 100644
--- a/h/services/bulk_api/lms_stats.py
+++ b/h/services/bulk_api/lms_stats.py
@@ -36,7 +36,7 @@ def _annotation_query(
         self,
         groups: list[str],
         h_userids: list[str] | None = None,
-        assignment_id: str | None = None,
+        assignment_ids: list[str] | None = None,
     ):
         query = (
             select(
@@ -77,10 +77,11 @@ def _annotation_query(
                 Group.authority_provided_id.in_(groups),
             )
         )
-        if assignment_id:
+        if assignment_ids:
             query = query.where(
-                AnnotationMetadata.data["lms"]["assignment"]["resource_link_id"].astext
-                == assignment_id,
+                AnnotationMetadata.data["lms"]["assignment"][
+                    "resource_link_id"
+                ].astext.in_(assignment_ids)
             )
 
         if h_userids:
@@ -106,7 +107,7 @@ def get_annotation_counts(
         groups: list[str],
         group_by: CountsGroupBy,
         h_userids: list[str] | None = None,
-        assignment_id: str | None = None,
+        assignment_ids: list[str] | None = None,
     ) -> list[AnnotationCounts]:
         """
         Get basic stats per user for an LMS assignment.
@@ -114,10 +115,10 @@ def get_annotation_counts(
         :param groups: List of "authority_provided_id" to filter groups by.
         :param group_by: By which column to aggregate the data.
         :param h_userids: List of User.userid to filter annotations by
-        :param assignment_id: ID of the assignment to filter annotations by
+        :param assignment_ids: ID of the assignment to filter annotations by
         """
         annos_query = self._annotation_query(
-            groups, h_userids=h_userids, assignment_id=assignment_id
+            groups, h_userids=h_userids, assignment_ids=assignment_ids
         ).cte("annotations")
 
         # Alias some columns
diff --git a/h/views/api/bulk/annotation_counts.json b/h/views/api/bulk/annotation_counts.json
index 06fe8aea9e3..44aea36f85b 100644
--- a/h/views/api/bulk/annotation_counts.json
+++ b/h/views/api/bulk/annotation_counts.json
@@ -31,10 +31,14 @@
         "h_userids": {
           "$ref": "#/$defs/nonEmptyStringArray"
         },
-        "assignment_id": {
-          "type": [
-            "string",
-            "null"
+        "assignment_ids": {
+          "anyOf": [
+            {
+              "ref": "#/$defs/nonEmptyStringArray"
+            },
+            {
+              "type": "null"
+            }
           ]
         }
       },
diff --git a/h/views/api/bulk/stats.py b/h/views/api/bulk/stats.py
index 39c36c84b45..b73490d35cd 100644
--- a/h/views/api/bulk/stats.py
+++ b/h/views/api/bulk/stats.py
@@ -31,7 +31,7 @@ def get_annotation_counts(request):
     stats = request.find_service(BulkLMSStatsService).get_annotation_counts(
         group_by=CountsGroupBy[data["group_by"].upper()],
         groups=query_filter["groups"],
-        assignment_id=query_filter.get("assignment_id"),
+        assignment_ids=query_filter.get("assignment_ids"),
         h_userids=query_filter.get("h_userids"),
     )
 
diff --git a/tests/unit/h/services/bulk_api/lms_stats_test.py b/tests/unit/h/services/bulk_api/lms_stats_test.py
index b18b041d67d..fcdca2c8015 100644
--- a/tests/unit/h/services/bulk_api/lms_stats_test.py
+++ b/tests/unit/h/services/bulk_api/lms_stats_test.py
@@ -17,7 +17,7 @@ def test_get_annotation_counts_by_user(
     ):
         stats = svc.get_annotation_counts(
             groups=[group.authority_provided_id],
-            assignment_id="ASSIGNMENT_ID",
+            assignment_ids=["ASSIGNMENT_ID"],
             group_by=CountsGroupBy.USER,
         )
 
diff --git a/tests/unit/h/views/api/bulk/stats_test.py b/tests/unit/h/views/api/bulk/stats_test.py
index b17b3630c20..862b4ece048 100644
--- a/tests/unit/h/views/api/bulk/stats_test.py
+++ b/tests/unit/h/views/api/bulk/stats_test.py
@@ -38,7 +38,7 @@ def test_get_annotation_counts(
         bulk_stats_service.get_annotation_counts.assert_called_once_with(
             group_by=CountsGroupBy.USER,
             groups=assignment_request["filter"]["groups"],
-            assignment_id=assignment_request["filter"]["assignment_id"],
+            assignment_ids=assignment_request["filter"]["assignment_ids"],
             h_userids=assignment_request["filter"]["h_userids"],
         )
         return_data = [
@@ -63,7 +63,7 @@ def assignment_request(self, pyramid_request):
             "filter": {
                 "groups": ["3a022b6c146dfd9df4ea8662178eac"],
                 "h_userids": ["acc:user@authority"],
-                "assignment_id": "ASSIGNMENT_ID",
+                "assignment_ids": ["ASSIGNMENT_ID"],
             },
         }