diff --git a/mps/code/eventdef.h b/mps/code/eventdef.h
index 8d495dcc0a6..0477c2bca0a 100644
--- a/mps/code/eventdef.h
+++ b/mps/code/eventdef.h
@@ -716,7 +716,8 @@
   PARAM(X,  3, W, condemned)    /* bytes condemned in generation */ \
   PARAM(X,  4, W, forwarded)    /* bytes forwarded from generation */ \
   PARAM(X,  5, W, preservedInPlace) /* bytes preserved in generation */ \
-  PARAM(X,  6, D, mortality)    /* updated mortality */
+  PARAM(X,  6, D, mortalityTrace) /* mortality (in last trace only) */ \
+  PARAM(X,  7, D, mortalityAverage) /* mortality (moving average) */
 
 #define EVENT_LabelPointer_PARAMS(PARAM, X) \
   PARAM(X,  0, P, pointer) /* pointer */ \
diff --git a/mps/code/locus.c b/mps/code/locus.c
index 3781a1408f5..e8919b159fe 100644
--- a/mps/code/locus.c
+++ b/mps/code/locus.c
@@ -214,8 +214,9 @@ static void genDescEndTrace(GenDesc gen, Trace trace)
     double mortality = 1.0 - survived / (double)stats->condemned;
     double alpha = LocusMortalityALPHA;
     gen->mortality = gen->mortality * (1 - alpha) + mortality * alpha;
-    EVENT7(TraceEndGen, trace->arena, trace, gen, stats->condemned,
-           stats->forwarded, stats->preservedInPlace, gen->mortality);
+    EVENT8(TraceEndGen, trace->arena, trace, gen, stats->condemned,
+           stats->forwarded, stats->preservedInPlace, mortality,
+           gen->mortality);
   }
 }
 
diff --git a/mps/tool/monitor b/mps/tool/monitor
index af349bb723e..96b9154b753 100755
--- a/mps/tool/monitor
+++ b/mps/tool/monitor
@@ -302,17 +302,22 @@ class Gen(EventHandler):
 
     def GenInit(self, t, event):
         self._serial = serial = event.serial
-        self._mortality = mortality = TimeSeries()
+        self._mortality_trace = mortality_trace = TimeSeries()
         self._model.add_time_series(
-            self, mortality, "fraction", f"mortality",
-            f"mortality of data in generation")
+            self, mortality_trace, "fraction", f"mortality.trace",
+            f"mortality of data in generation, per trace")
+        self._mortality_average = mortality_average = TimeSeries()
+        self._model.add_time_series(
+            self, mortality_average, "fraction", f"mortality.avg",
+            f"mortality of data in generation, moving average")
         self._ref_size = ref_size = TimeSeries()
         self._model.add_time_series(
             self, ref_size, "bytes", f"ref",
             f"size of segments referencing generation")
 
     def TraceEndGen(self, t, event):
-        self._mortality.append(t, event.mortality)
+        self._mortality_trace.append(t, event.mortalityTrace)
+        self._mortality_average.append(t, event.mortalityAverage)
 
 
 class Arena(EventHandler):