As the CISO of a publicly traded company, ensuring the availability of systems is critical for supporting business operations and customer trust. To achieve this, I would implement a multi-layered approach.

1. Redundancy and Failover Systems: I would ensure all critical systems have redundant servers and failover mechanisms, either on-premises or in the cloud. This would protect against hardware failures or data center outages by allowing operations to switch seamlessly to backup systems without interruption.

2. Regular Backups: Implementing frequent, automated backups of all essential data is crucial. These backups would be stored in multiple, geographically diverse locations to safeguard against disasters. This ensures that in the event of a system failure, data can be quickly restored to support availability.

3. Distributed Denial of Service (DDoS) Protection: DDoS attacks can severely affect system availability. I would deploy advanced DDoS protection tools, like traffic filtering and load balancing, to mitigate the risk of such attacks overwhelming our systems and keeping services online.

4. Continuous Monitoring and Incident Response: Having real-time monitoring and an established incident response plan is essential to quickly identify and resolve any issues that could change availability. This allows for proactive detection and mitigation of potential outages before they cause major disruptions.

By implementing these strategies, I can ensure that systems are still available and resilient against potential disruptions.