diff --git a/docs/changelog/130521.yaml b/docs/changelog/130521.yaml
new file mode 100644
index 0000000000000..e5308ea8dc134
--- /dev/null
+++ b/docs/changelog/130521.yaml
@@ -0,0 +1,5 @@
+pr: 130521
+summary: Trim to size lists created in source fetchers
+area: Search
+type: bug
+issues: []
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/ArraySourceValueFetcher.java b/server/src/main/java/org/elasticsearch/index/mapper/ArraySourceValueFetcher.java
index 6c9c88f767617..fa835e4356667 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/ArraySourceValueFetcher.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/ArraySourceValueFetcher.java
@@ -56,7 +56,7 @@ public ArraySourceValueFetcher(Set<String> sourcePaths, Object nullValue) {
 
     @Override
     public List<Object> fetchValues(Source source, int doc, List<Object> ignoredValues) {
-        List<Object> values = new ArrayList<>();
+        ArrayList<Object> values = new ArrayList<>();
         for (String path : sourcePaths) {
             Object sourceValue = source.extractValue(path, nullValue);
             if (sourceValue == null) {
@@ -70,6 +70,7 @@ public List<Object> fetchValues(Source source, int doc, List<Object> ignoredValu
                 ignoredValues.add(sourceValue);
             }
         }
+        values.trimToSize();
         return values;
     }
 
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/NestedValueFetcher.java b/server/src/main/java/org/elasticsearch/index/mapper/NestedValueFetcher.java
index df9e348dc9fbc..008bbdbd0005b 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/NestedValueFetcher.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/NestedValueFetcher.java
@@ -42,7 +42,7 @@ public NestedValueFetcher(String nestedField, FieldFetcher nestedFieldFetcher) {
 
     @Override
     public List<Object> fetchValues(Source source, int doc, List<Object> includedValues) throws IOException {
-        List<Object> nestedEntriesToReturn = new ArrayList<>();
+        ArrayList<Object> nestedEntriesToReturn = new ArrayList<>();
         Map<String, Object> filteredSource = new HashMap<>();
         Map<String, Object> stub = createSourceMapStub(filteredSource);
         List<?> nestedValues = XContentMapValues.extractNestedSources(nestedFieldPath, source.source());
@@ -69,6 +69,7 @@ public List<Object> fetchValues(Source source, int doc, List<Object> includedVal
                 nestedEntriesToReturn.add(nestedEntry);
             }
         }
+        nestedEntriesToReturn.trimToSize();
         return nestedEntriesToReturn;
     }
 
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/SourceValueFetcher.java b/server/src/main/java/org/elasticsearch/index/mapper/SourceValueFetcher.java
index a65a3cd017954..7d1e722200ba3 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/SourceValueFetcher.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/SourceValueFetcher.java
@@ -55,7 +55,7 @@ public SourceValueFetcher(Set<String> sourcePaths, Object nullValue) {
 
     @Override
     public List<Object> fetchValues(Source source, int doc, List<Object> ignoredValues) {
-        List<Object> values = new ArrayList<>();
+        ArrayList<Object> values = new ArrayList<>();
         for (String path : sourcePaths) {
             Object sourceValue = source.extractValue(path, nullValue);
             if (sourceValue == null) {
@@ -92,6 +92,7 @@ public List<Object> fetchValues(Source source, int doc, List<Object> ignoredValu
                 }
             }
         }
+        values.trimToSize();
         return values;
     }