diff --git a/firestore.indexes.json b/firestore.indexes.json
index 064f6f2f..e0cee632 100644
--- a/firestore.indexes.json
+++ b/firestore.indexes.json
@@ -337,6 +337,20 @@
           "order": "DESCENDING"
         }
       ]
+    },
+    {
+      "collectionGroup": "portfolioHistory",
+      "queryScope": "COLLECTION",
+      "fields": [
+        {
+          "fieldPath": "userId",
+          "order": "ASCENDING"
+        },
+        {
+          "fieldPath": "timestamp",
+          "order": "ASCENDING"
+        }
+      ]
     }
   ],
   "fieldOverrides": [