diff --git a/trader.go b/trader.go
index fd3e9f9..ef1fc23 100644
--- a/trader.go
+++ b/trader.go
@@ -454,6 +454,12 @@ func (t *Trader) checkExit(pos *ArbPosition, bgP, hlP, diffPct float64, notifier
 		exitReason = "价差收敛,止盈平仓"
 	}
 
+	// Stop-loss: spread reversed (went negative)
+	if diffPct < -0.02 {
+		shouldExit = true
+		exitReason = "价差反转,止损平仓"
+	}
+
 	if elapsed > 30*time.Minute {
 		shouldExit = true
 		exitReason = "超时平仓"