Update app.py

app.py

@@ -21,7 +21,7 @@ TICKERS = {
     "Apple": "AAPL",
     "Facebook": "META",
     "Google": "GOOGL",
-    "NASDAQ": "^IXIC"  # indice NASDAQ per confronto aggregato
+    "NASDAQ": "^IXIC"
 }
 
 # --- FETCH STOCK PRICES ROBUSTLY ---
@@ -31,6 +31,10 @@ for company, ticker in TICKERS.items():
     end_date = pd.Timestamp.today()
     df_prices = yf.download(ticker, start=start_date, end=end_date)
 
+    # Flatten MultiIndex columns if present
+    if isinstance(df_prices.columns, pd.MultiIndex):
+        df_prices.columns = ['_'.join([str(c) for c in col]).strip() for col in df_prices.columns]
+
     # Ensure 'Close' column exists
     if 'Close' not in df_prices.columns:
         if 'Adj Close' in df_prices.columns: