diff --git a/static/js/activity.js b/static/js/activity.js
index b6eab251cb..23676fcbc3 100644
--- a/static/js/activity.js
+++ b/static/js/activity.js
@@ -39,6 +39,30 @@ $("html").on("mousemove", function () {
 
 var presence_info = {};
 
+var huddle_timestamps = new Dict();
+
+exports.process_loaded_messages = function (messages) {
+    _.each(messages, function (message) {
+        if (message.type === 'private') {
+            if (message.reply_to.indexOf(',') > 0) {
+                var old_timestamp = huddle_timestamps.get(message.reply_to);
+
+                if (!old_timestamp || (old_timestamp < message.timestamp)) {
+                    huddle_timestamps.set(message.reply_to, message.timestamp);
+                }
+            }
+        }
+    });
+};
+
+exports.get_huddles = function () {
+    var huddles = huddle_timestamps.keys();
+    huddles = _.sortBy(huddles, function (huddle) {
+        return huddle_timestamps.get(huddle);
+    });
+    return huddles.reverse();
+};
+
 function sort_users(users, presence_info) {
     // TODO sort by unread count first, once we support that
     users.sort(function (a, b) {
diff --git a/zerver/tests/frontend/node/activity.js b/zerver/tests/frontend/node/activity.js
index 3ccf6fd09a..d138072904 100644
--- a/zerver/tests/frontend/node/activity.js
+++ b/zerver/tests/frontend/node/activity.js
@@ -46,3 +46,45 @@ var activity = require('js/activity.js');
         'alice@zulip.com'
     ]);
 }());
+
+(function test_process_loaded_messages() {
+
+    var huddle1 = 'bar@zulip.com,foo@zulip.com';
+    var timestamp1 = 1382479029; // older
+
+    var huddle2 = 'alice@zulip.com,bob@zulip.com';
+    var timestamp2 = 1382479033; // newer
+
+    var old_timestamp = 1382479000;
+
+    var messages = [
+        {
+            type: 'private',
+            reply_to: huddle1,
+            timestamp: timestamp1
+        },
+        {
+            type: 'stream'
+        },
+        {
+            type: 'private',
+            reply_to: 'ignore@zulip.com'
+        },
+        {
+            type: 'private',
+            reply_to: huddle2,
+            timestamp: timestamp2
+        },
+        {
+            type: 'private',
+            reply_to: huddle2,
+            timestamp: old_timestamp
+        }
+    ];
+
+    activity.process_loaded_messages(messages);
+
+    assert.deepEqual(activity.get_huddles(), [huddle2, huddle1]);
+}());
+
+