diff --git a/src/constants.json b/src/constants.json
index a4649e09c31..806b3790c12 100644
--- a/src/constants.json
+++ b/src/constants.json
@@ -32,7 +32,8 @@
     "BID_RESPONSE": "bidResponse",
     "BID_WON": "bidWon",
     "SET_TARGETING": "setTargeting",
-    "REQUEST_BIDS": "requestBids"
+    "REQUEST_BIDS": "requestBids",
+    "ADD_AD_UNITS": "addAdUnits"
   },
   "EVENT_ID_PATHS": {
     "bidWon": "adUnitCode"
diff --git a/src/prebid.js b/src/prebid.js
index 4d94fb475ce..4aeb5482100 100644
--- a/src/prebid.js
+++ b/src/prebid.js
@@ -28,6 +28,7 @@ const { syncUsers, triggerUserSyncs } = userSync;
 
 var BID_WON = CONSTANTS.EVENTS.BID_WON;
 var SET_TARGETING = CONSTANTS.EVENTS.SET_TARGETING;
+var ADD_AD_UNITS = CONSTANTS.EVENTS.ADD_AD_UNITS;
 
 var auctionRunning = false;
 var bidRequestQueue = [];
@@ -447,6 +448,8 @@ $$PREBID_GLOBAL$$.addAdUnits = function (adUnitArr) {
     adUnitArr.transactionId = utils.generateUUID();
     $$PREBID_GLOBAL$$.adUnits.push(adUnitArr);
   }
+  // emit event
+  events.emit(ADD_AD_UNITS);
 };
 
 /**