The data center that supports CME Group Inc., one of the world’s largest derivatives exchanges, said it has bolstered its backup cooling capacity after overheating sparked a catastrophic 10-hour outage that roiled world markets on Friday.
CyrusOne — which owns the facility in the suburban town of Aurora, Illinois, some 50 miles (80 kilometers) from Chicago — said it had restored “stable and secure” operations and that it had installed “additional redundancy to the cooling systems,” according to a statement to Bloomberg News on Sunday. The data center serves as the hub for trillions of dollars of derivatives that change hands each day across equity, currency, bond and commodity markets globally.
Futures trading opened normally at 6 p.m. Sunday, with contracts on the S&P 500 Index down 0.1% in early trading. Treasury futures edged lower and oil climbed.
CME’s markets were out for more than 10 hours on Friday after a failure in the cooling system at the facility, run by privately owned CyrusOne. While CME’s disaster recovery plan calls for a move to a data center in the New York area, the exchange opted against switching to a backup facility because the information it had pointed to a brief outage, a person familiar with the matter said on Friday.
The snafu at the Aurora data center disrupted markets from Tokyo to London, bringing to a halt trading in everything from gold to oil and interest rates. Even after trading was largely restored on Friday, disruptions extended well into the US session, with CME Direct, a trading platform provided by the exchange, offline for most of the day.
The outage underscored a vulnerability in increasingly integrated global markets that rely on a handful of dominant exchanges. It also raises questions about the contingency plans of CME and its heavy reliance on the data center it sold in 2016 to CyrusOne, a company now owned by KKR & Co. and Global Infrastructure Partners.
It’s unclear what exactly happened to CyrusOne’s cooling system, but temperatures at the complex soared to over 100F (38C) during the outage. That’s even as the data center offered a redundancy system and free cooling when temperatures fall below 30F, according to information on CyrusOne’s website.
Exchange operators tend to place their matching engine, where bids and offers are matched, in one place to avoid the cost of setting up multiple connections over various locations. The New York Stock Exchange and Nasdaq, the biggest equities exchanges, have partnerships with data centers located in New Jersey. Chicago-based CME keeps their data centers concentrated in their home state of Illinois.
It’s difficult for exchanges to move their data centers because traders like to have infrastructure near or in the data center itself to ensure information travels faster, giving them a slim advantage over others that aren’t nearby. Building out infrastructure elsewhere takes time and results in costs for firms.
The Commodity Futures Trading Commission, the top US derivatives regulator, said it was aware of the situation and conducting routine market monitoring, according to a spokesperson.
Photo: A CyrusOne data center in Aurora, Illinois, US, on Friday, Nov 28, 2025. The Chicago Mercantile Exchange began restoring most trading operations after a technical outage, caused by a cooling-system malfunction at a Chicago-area data center operated by CyrusOne, that had crippled key parts of financial markets.
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