diff --git a/ChangeLog b/ChangeLog
index 8437b99bad..56c46a667a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Nov 25 17:07:06 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* NEWS: add an "Implementation changes" section.
+
 Tue Nov 25 16:09:28 2014  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/net/http.rb:  Do not attempt SSL session resumption when the
diff --git a/NEWS b/NEWS
index bbce1b5765..94e8abc2a6 100644
--- a/NEWS
+++ b/NEWS
@@ -321,3 +321,16 @@ with all sufficient information, see the ChangeLog file.
 * jemalloc is optionally supported via `./configure --with-jemalloc`
   jemalloc may be suitable when system malloc is slow or prone
   to fragmentation.  [Feature #9113]
+
+=== Implementation changes
+
+* GC
+    * Most symbols which are returned by String#to_sym and
+      String#intern are GC-able [Feature #9634]
+    * Introduce incremental marking for major GC. [Feature #10137]
+
+* VM
+    * Use frozen string literals for Hash#[] and Hash#[]=
+    * Fast keyword arguments passing [Feature #10440]
+    * Allow to receive huge splatted array by a rest argument
+      [Feature #10440]