What is the most pricey trojan horse in history?

The most expensive computer system virus in history is the Love Bug virus, which was launched in 2000. Once a computer was infected, the virus would erase essential files and spread itself to other computer systems.  https://sakeradvantage.com/?p=929 The Love Bug infection was eventually stopped by a team of anti-virus researchers who produced a vaccine that could protect computer systems from the infection.