What is the most pricey trojan horse in history?

The most costly virus in history is the Love Bug virus, which was launched in 2000. This virus caused an estimated $5.5 billion in damage worldwide, making it the most costly infection ever. The Love Bug virus was a mass-mailing worm that infected over 45 million computers in just a couple of days. The virus spread rapidly by emailing itself to everyone in the victim's address book. When a computer was infected, the virus would erase essential files and spread itself to other computer systems.  https://tastykoreachannel.com/?p=2837 The Love Bug virus was ultimately dropped in a team of anti-virus researchers who created a vaccine that could protect computer systems from the infection.