Interesting is that all they did was take down the website where all company anouncements are made - a simple DDOS would do this. As a result, the exchange suspended the shares of companies that were due to release price-sensitive information. It is a huge impact for a relatively simple and low-tech attack.

This could be mitigated by placing all announcement docs on two large CDNs as a backup and switch over if the main system fails.

Seem HK Exchange don't expect such DDoS for the simple document hosting platform.