Authorities are reexamining an August outage at the London Stock Exchange that was initially attributed to a software glitch. The disruption prevented traders from buying or selling shares for more than 90 minutes, and impacted prices on two stock indexes. The incident could have been caused by hackers trying to destabilise markets for their own gain or even set the stage for a more nefarious scheme in the future. The lengthy time to identification reflects the difficulty that many companies have when identifying and addressing cyber threats.
https://www.zdnet.com/article/uk-government-investigates-possible-cyberattack-link-to-london-stock-exchange-outage/