diff --git a/web/client-api/src/main/java/io/deephaven/web/client/api/subscription/ViewportData.java b/web/client-api/src/main/java/io/deephaven/web/client/api/subscription/ViewportData.java
index d21247c2d10..c998321be4c 100644
--- a/web/client-api/src/main/java/io/deephaven/web/client/api/subscription/ViewportData.java
+++ b/web/client-api/src/main/java/io/deephaven/web/client/api/subscription/ViewportData.java
@@ -492,11 +492,11 @@ public MergeResults merge(DeltaUpdates updates) {
             }
         }
 
-        for (Iterator<Integer> it = updated.modified.iterator(); it.hasNext();) {
-            int ii = it.next();
-            updated.added.remove(ii);
-            updated.removed.remove(ii);
-        }
+        // exclude added items from being marked as modified, since we're hiding shifts from api consumers
+        updated.modified.removeAll(updated.added);
+
+        // Any position which was both added and removed should instead be marked as modified, this cleans
+        // up anything excluded above that didn't otherwise make sense
         for (Iterator<Integer> it = updated.removed.iterator(); it.hasNext();) {
             int ii = it.next();
             if (updated.added.remove(ii)) {