diff --git a/webservice/api_blueprint_portfolio.py b/webservice/api_blueprint_portfolio.py
index f8a715a..6ee8a37 100644
--- a/webservice/api_blueprint_portfolio.py
+++ b/webservice/api_blueprint_portfolio.py
@@ -24,7 +24,7 @@ def get_portfolio():
         for row in transactions:
             if row.symbol in return_portfolio:
                 return_portfolio[row.symbol]['count'] += row.count
-                return_portfolio[row.symbol]['last_transaction'] += row.time
+                return_portfolio[row.symbol]['last_transaction'] = row.time
             else:
                 return_portfolio[row.symbol] = {"count": row.count, "last_transaction": row.time}