diff --git a/lib/engine/stock_movement.rb b/lib/engine/stock_movement.rb
index f7ddfb8563..9879ee9e97 100644
--- a/lib/engine/stock_movement.rb
+++ b/lib/engine/stock_movement.rb
@@ -8,6 +8,8 @@ def initialize(market)
 
     def share_price(coordinates)
       row, column = coordinates
+      return if row.negative? || column.negative?
+
       @market.market[row]&.[](column)
     end