diff --git a/trader.py b/trader.py
index 277841a..12f6787 100644
--- a/trader.py
+++ b/trader.py
@@ -497,9 +497,10 @@ class Trader(Account):
             
             next_position = pd.DataFrame({'stock_code': next_margin_list + next_normal_list})
             next_position['date'] = date
+            
             # 融资融券数量
             margin_num = len(next_margin_list)
-            next_position['weight'] = self.get_weight(date, 1 + (margin_num / self.num), next_position)
+            next_position['weight'] = self.get_weight(date, 1 + (margin_num / self.num), untradable_list, next_position)
             next_position['margin_trade'] = 0
             next_position = next_position.set_index(['stock_code'])
             next_position.loc[next_margin_list, 'margin_trade'] = 1
@@ -633,7 +634,7 @@ class Trader(Account):
         if cur_pos['weight'].sum() == 0:
             pnl = 0
         else:
-            cash = 1 - cur_pos['weight'].sum()
+            cash = max(0, 1 - cur_pos['weight'].sum())
             pnl = ((cur_pos['end_weight'].sum() + cash) / (cur_pos['weight'].sum() + cash)) - 1
         self.account *= 1+pnl
         self.account_history = self.account_history.append({