diff --git a/ANNOTATE/web/static/js/chart_manager.js b/ANNOTATE/web/static/js/chart_manager.js
index 44da8f6..485d9e9 100644
--- a/ANNOTATE/web/static/js/chart_manager.js
+++ b/ANNOTATE/web/static/js/chart_manager.js
@@ -3090,13 +3090,35 @@ class ChartManager {
         
         targetPrice = currentPrice + priceChange;
         
-        // Sanity check: Don't let target price go to 0 or negative
+        // CRITICAL VALIDATION: Filter out invalid trend lines that would break chart zoom
+        // Don't draw if:
+        // 1. Target price is <= 0 or not finite
+        // 2. Target price is more than 10% away from current price (likely bad prediction)
+        // 3. Price change is too extreme (> 50% of current price)
+        const priceChangePercent = Math.abs((targetPrice - currentPrice) / currentPrice);
+        
         if (targetPrice <= 0 || !isFinite(targetPrice)) {
-            console.warn('Invalid target price calculated:', targetPrice, 'using current price instead');
-            targetPrice = currentPrice;
+            console.warn('Skipping trend line: Invalid target price:', targetPrice);
+            return; // Don't draw this trend line
         }
         
-        // Draw trend ray
+        if (priceChangePercent > 0.10) {
+            console.warn('Skipping trend line: Price change too large:', 
+                        `${(priceChangePercent * 100).toFixed(1)}% (${currentPrice.toFixed(2)} -> ${targetPrice.toFixed(2)})`);
+            return; // Don't draw this trend line
+        }
+        
+        // Additional check: Ensure target price is within reasonable bounds
+        const minReasonablePrice = currentPrice * 0.5;  // 50% below
+        const maxReasonablePrice = currentPrice * 1.5;  // 50% above
+        
+        if (targetPrice < minReasonablePrice || targetPrice > maxReasonablePrice) {
+            console.warn('Skipping trend line: Target price out of reasonable bounds:', 
+                        `${targetPrice.toFixed(2)} (current: ${currentPrice.toFixed(2)})`);
+            return; // Don't draw this trend line
+        }
+        
+        // All validations passed - draw the trend ray
         shapes.push({
             type: 'line',
             x0: lastTimestamp,