diff --git a/strategies/shared/signals/selectors.py b/strategies/shared/signals/selectors.py
index 2e81484..3b5dd9c 100644
--- a/strategies/shared/signals/selectors.py
+++ b/strategies/shared/signals/selectors.py
@@ -151,6 +151,11 @@ class TopNSelector(SignalGenerator):
                 if should:
                     current_held = target
                     last_rebalance_idx = i
+            else:
+                # 目标信号为空（所有标的动量得分低于min_score），清仓
+                # 不继续持有负动量标的，转为空仓
+                current_held = ''
+                last_rebalance_idx = i
             
             signals.append(current_held)