AURORA, IL / December 1, 2025 — Data center operator CyrusOne has bolstered backup cooling capacity at its Aurora, Illinois, facility following a system failure last week that triggered a multi-hour trading outage at CME Group, the world’s largest exchange operator.

The outage on Friday forced CME to halt trading across stocks, bonds, commodities, and currencies, highlighting the exchange’s reliance on the Aurora data center.

"CyrusOne has restored stable and secure operations at the Chicago 1 (CHI1) data center," the company said Monday, adding that additional redundancy has been installed to enhance operational continuity.

Bloomberg News first reported the development. CME sold the Aurora data center to CyrusOne in 2016. CyrusOne, which operates more than 55 data centers globally, is owned by KKR & Co and Global Infrastructure Partners.

The incident underscores the strain on data center cooling systems amid the growing adoption of AI-powered applications and the surge in outsourced storage worldwide.