diff --git a/src/pages/analysis/monte_carlo_page.py b/src/pages/analysis/monte_carlo_page.py
index b4a97c6..443ea74 100644
--- a/src/pages/analysis/monte_carlo_page.py
+++ b/src/pages/analysis/monte_carlo_page.py
@@ -19,11 +19,14 @@ class MonteCarloSimulator:
             num_simulations (int): Number of simulation paths
             time_horizon (int): Number of days to simulate
         """
-        self.data = data
+        # Make a copy and standardize column names
+        self.data = data.copy()
+        self.data.columns = [col.capitalize() for col in self.data.columns]
+        
         self.num_simulations = num_simulations
         self.time_horizon = time_horizon
-        self.returns = np.log(data['Close'] / data['Close'].shift(1)).dropna()
-        self.last_price = data['Close'].iloc[-1]
+        self.returns = np.log(self.data['Close'] / self.data['Close'].shift(1)).dropna()
+        self.last_price = self.data['Close'].iloc[-1]
         self.drift = self.returns.mean()
         self.volatility = self.returns.std()