The main threat to GPS systems is known as GPS spoofing whereby an interference in GPS receiver is fooled into tracking counterfeit GPS signals. A possible attacks to GPS system would impact many sector with serious consequences. A typical attack can be addressed with the intent to sabotage the times on one of the global stock exchanges, it could cause the block of the activities once the automated trading systems notice the anomaly. The GPS are also used in other areas, from environmental control to the financial sector.”]
Source: http://securityaffairs.co/wordpress/2845/hacking/gps-spoofing-old-threat-and-new-problems.html