diff --git a/MainWindow.axaml b/MainWindow.axaml
index 53ed631..9c8cf0f 100644
--- a/MainWindow.axaml
+++ b/MainWindow.axaml
@@ -164,6 +164,7 @@
                                 </Button>
                                 <Button HorizontalAlignment="Stretch" MinWidth="240"
                                         HorizontalContentAlignment="Center" x:Name="BtnCombineIntersect"
+                                        Click="BtnCombineIntersection_OnClick"
                                         Margin="0,0,0,10">
                                     <StackPanel Orientation="Horizontal">
                                         <LucideIcon Kind="SquaresIntersect" Width="36" Height="36" />
diff --git a/MainWindow.axaml.cs b/MainWindow.axaml.cs
index 777f0e8..0744e32 100644
--- a/MainWindow.axaml.cs
+++ b/MainWindow.axaml.cs
@@ -512,4 +512,14 @@ public partial class MainWindow : Window
 
         StartCombine(list, Convert.ToInt32(LstCustomers.SelectedItem.ToString().Split(" - ")[0]), "union");
     }
+
+    private void BtnCombineIntersection_OnClick(object? sender, RoutedEventArgs e)
+    {
+        var list = new List<KasAddressList>();
+        foreach (var item in LstCustomerAdressSets.SelectedItems)
+            list.Add(Settings._instance.addressSets.GetAddressSetByID(
+                Convert.ToInt32(item.ToString().Split(" - ")[0])));
+
+        StartCombine(list, Convert.ToInt32(LstCustomers.SelectedItem.ToString().Split(" - ")[0]), "intersection");
+    }
 }
\ No newline at end of file
diff --git a/Tasks/CombineAddresses.cs b/Tasks/CombineAddresses.cs
index aaaf76d..c0a9e7d 100644
--- a/Tasks/CombineAddresses.cs
+++ b/Tasks/CombineAddresses.cs
@@ -22,6 +22,7 @@ public class CombineAddresses
         {
             if (type == "difference") return Difference(address_lists);
             if (type == "union") return Union(address_lists);
+            if (type == "intersection") return Intersection(address_lists);
 
             return null;
         });
@@ -115,12 +116,10 @@ public class CombineAddresses
                 result.KasPersons.Add(person);
 
             progress.Increment();
-            if (progress.LogAction != null)
-            {
-                var logMessage =
-                    $"Person mit refsid {person.refsid} verglichen mit {restUnion.Count} Personen des Restes.";
-                await Dispatcher.UIThread.InvokeAsync(() => progress.LogAction?.Invoke(logMessage));
-            }
+            if (progress.LogAction == null) continue;
+            var logMessage =
+                $"Person mit refsid {person.refsid} verglichen mit {restUnion.Count} Personen des Restes.";
+            await Dispatcher.UIThread.InvokeAsync(() => progress.LogAction?.Invoke(logMessage));
         }
 
         return result;
@@ -148,7 +147,51 @@ public class CombineAddresses
             var logMessage =
                 $"{percent:F1}%: Person mit {person.refsid} hinzugefügt (aktuell {result.KasPersons.Count} Einträge)";
 
-            // Sicher, nicht blockierend:
+            if (progress == null) continue;
+            if (Dispatcher.UIThread.CheckAccess())
+                progress.LogAction?.Invoke(logMessage);
+            else
+                Dispatcher.UIThread.Post(() => progress.LogAction?.Invoke(logMessage));
+        }
+
+        return result;
+    }
+
+
+    public async Task<KasAddressList> MoveDuplicatesToNew()
+    {
+        return null;
+    }
+
+    public async Task<KasAddressList> Intersection(List<KasAddressList> address_lists, Progress progress = null)
+    {
+        var result = new KasAddressList("intersection");
+
+        if (address_lists == null || address_lists.Count == 0)
+            return result;
+
+        // Nur die erste Liste als Ausgangspunkt verwenden
+        var baseList = address_lists[0];
+        var otherLists = address_lists.Skip(1).ToList();
+
+        var total = baseList.KasPersons.Count;
+        var processed = 0;
+
+        foreach (var person in baseList.KasPersons)
+        {
+            // Prüfen, ob Person in *allen* anderen Listen vorkommt
+            var isInAll = otherLists.All(list =>
+                list.KasPersons.Any(existing => CompareAddresses(existing, person)));
+
+            if (isInAll)
+                result.KasPersons.Add(person);
+
+            processed++;
+            var percent = processed / (double)total * 100;
+            var logMessage =
+                $"{percent:F1}%: Person mit {person.refsid} geprüft – {(isInAll ? "in allen enthalten" : "nicht überall vorhanden")}";
+
+            // Sicher und nicht blockierend loggen
             if (progress != null)
             {
                 if (Dispatcher.UIThread.CheckAccess())
@@ -162,16 +205,6 @@ public class CombineAddresses
     }
 
 
-    public async Task<KasAddressList> MoveDuplicatesToNew()
-    {
-        return null;
-    }
-
-    public async Task<KasAddressList> Intersection()
-    {
-        return null;
-    }
-
     public async Task<KasAddressList> SymmetricDifference()
     {
         return null;