diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 00000000..5008ddfc
Binary files /dev/null and b/.DS_Store differ
diff --git a/quick_trade/trading_sys.py b/quick_trade/trading_sys.py
index 54b31254..daf54d54 100644
--- a/quick_trade/trading_sys.py
+++ b/quick_trade/trading_sys.py
@@ -941,7 +941,7 @@ def backtest(self,
         return self.backtest_out
 
     def multi_backtest(self,
-                       tickers: List[str],
+                       tickers: Iterable[str],
                        strategy_name: str = 'strategy_macd',
                        strategy_kwargs: Dict[str, Any] = {},
                        deposit: float = 10_000.0,