diff --git a/lib/pt_trading/trading_pair.py b/lib/pt_trading/trading_pair.py
index 5b6da8c..8ba825d 100644
--- a/lib/pt_trading/trading_pair.py
+++ b/lib/pt_trading/trading_pair.py
@@ -376,16 +376,16 @@ class TradingPair:
             open_trades = self.user_data_["open_trades"]
             if len(open_trades) == 0:
                 return 0.0
-            def _stock_return(stock: str) -> float:
-                stock_open_trades = open_trades[open_trades["symbol"] == stock]
-                stock_sign = -1 if stock_open_trades["action"].iloc[0]  == "SELL" else 1
-                stock_price = predicted_row[f"{self.price_column_}_{stock}"]
-                stock_return = stock_sign * (stock_price - stock_open_trades["price"].iloc[0]) / stock_open_trades["price"].iloc[0]
-                return float(stock_return)
+            def _single_instrument_return(symbol: str) -> float:
+                instrument_open_trades = open_trades[open_trades["symbol"] == symbol]
+                instrument_sign = -1 if instrument_open_trades["action"].iloc[0]  == "SELL" else 1
+                instrument_price = predicted_row[f"{self.price_column_}_{symbol}"]
+                instrument_return = instrument_sign * (instrument_price - instrument_open_trades["price"].iloc[0]) / instrument_open_trades["price"].iloc[0]
+                return float(instrument_return)
             
-            stock_a_return = _stock_return(self.symbol_a_)
-            stock_b_return = _stock_return(self.symbol_b_)
-            return (stock_a_return + stock_b_return) * 100.0
+            instrument_a_return = _single_instrument_return(self.symbol_a_)
+            instrument_b_return = _single_instrument_return(self.symbol_b_)
+            return (instrument_a_return + instrument_b_return) * 100.0
         return 0.0
         
     def __repr__(self) -> str: