The CME Group shut down trading across all its major derivatives markets after a catastrophic cooling system failure at CyrusOne’s CHI1 data center in the Chicago area on Thursday, November 27, 2025. The outage, which began at 8:40 p.m. CT, froze global markets just hours before the critical expiration of key futures contracts and amid historically thin post-Thanksgiving liquidity. By 3:44 a.m. GMT on Friday, November 28, market data had stopped updating entirely—leaving traders in the dark on S&P 500, Nasdaq 100, and Dow Jones futures. The disruption, one of the longest in memory, exposed the fragile underpinnings of modern finance: a single data center’s HVAC failure could bring the world’s largest derivatives exchange to a standstill.
How a Cooling System Took Down Global Markets
It wasn’t a cyberattack. Not a power surge. Not even a software bug. Just a broken chiller.
CyrusOne confirmed the issue was isolated to its CHI1 facility, where CME Group hosts its core trading infrastructure. Cooling systems in these facilities aren’t just about comfort—they’re critical to prevent server overheating that can trigger cascading failures. When the primary and backup chillers failed simultaneously, servers began throttling performance, then shutting down entirely. Market data feeds went silent. Order matching engines froze. The EBS foreign exchange platform, which normally moves nearly $60 billion a day, couldn’t update euro/dollar or dollar/yen quotes. Traders couldn’t hedge risk. Institutions couldn’t rebalance portfolios. The CME Group’s FedWatch barometer, a vital tool for predicting Federal Reserve policy, went dark.
"It was a nightmare scenario," said one institutional trader at Ultima Markets. "You’re holding positions with no live pricing. No way to close. No way to know if you’re underwater or not. You’re just sitting there, praying the systems come back before the market opens."
Market Chaos During the Holiday Lull
The timing couldn’t have been worse. The U.S. was in the middle of a holiday-thinned trading week. Volume was already at 40% of normal levels. Several major futures contracts—like the December S&P 500 and Treasury futures—were set to expire on Friday. Normally, these expirations trigger predictable volatility. But this time, there was no price discovery. No volume. No clarity.
"You don’t need a lot of volume to cause chaos," explained a former CME risk officer. "You just need one critical node to fail—and the whole structure becomes brittle."
By 5:30 a.m. ET on November 28, BrokerTec EU markets reopened—its fixed income focus spared by a separate infrastructure setup. But the rest of CME Group’s platforms—Globex, EBS, BMD—remained offline. The silence stretched for over 13 hours. When trading finally resumed at 9:30 a.m. ET, markets opened with a 1.2% gap in the S&P 500 futures, reflecting the pent-up pressure of the outage.
Why This Isn’t Just a Tech Glitch
This was CME Group’s first major outage since 2019. In the intervening years, the exchange invested heavily in redundancy, cloud partnerships, and resilience upgrades—including a March 2025 collaboration with Google Cloud to explore tokenization and distributed ledger technologies. Yet none of that mattered when the cooling system failed.
"We’ve been so focused on cybersecurity and cloud migration," said Arslan Butt, author of the FX Leaders report, "that we’ve underestimated the physical vulnerabilities. A chiller isn’t a firewall. But it’s just as important."
The incident also came just weeks before CME Group planned to launch new spot-quoted crypto futures for XRP and Solana on December 15, 2025. Regulatory approval was still pending, but the outage raised fresh questions about whether its infrastructure could handle the added load—and the scrutiny that comes with crypto trading.
What’s Next for Financial Infrastructure?
CME Group shares rose over 20% year-to-date as of November 28, 2025, a sign investors still trust its long-term model. But the market’s confidence won’t survive another outage like this.
Regulators are expected to demand a full audit of critical data center dependencies. The Commodity Futures Trading Commission (CFTC) has already signaled it will review the incident. Meanwhile, other exchanges—like ICE and Nasdaq—are quietly reviewing their own third-party hosting agreements.
"This wasn’t an attack," said a senior infrastructure analyst at LSEG. "It was a reminder. Finance runs on servers. Servers run on cooling. Cooling runs on electricity. And electricity runs on human maintenance. One broken valve, one missed filter change, and the entire global financial system holds its breath."
For now, CME Group is working with CyrusOne and specialized mechanical contractors to install redundant cooling loops and real-time temperature monitoring. But the real question isn’t about hardware. It’s about mindset. When your entire business depends on a machine that can’t feel heat, how do you prepare for the inevitable?
Frequently Asked Questions
How long were markets down, and what time did trading resume?
Trading was halted for approximately 13.5 hours, beginning at 8:40 p.m. CT on November 27, 2025, and fully restored by 9:30 a.m. ET on November 28, 2025. BrokerTec EU reopened earlier at 5:30 a.m. ET, but all major CME Group platforms—including Globex and EBS—remained offline until the morning session.
Which specific markets were affected by the outage?
All CME Group platforms were impacted: CME Globex (futures and options), EBS (foreign exchange), and BMD. This included key contracts like S&P 500, Nasdaq 100, Dow Jones futures, Treasury bonds, commodities (crude oil, gold), and major currency pairs such as EUR/USD and USD/JPY. The FedWatch barometer, used to gauge Fed rate cut expectations, also stopped updating.
Why did a cooling failure cause such a widespread outage?
Data centers like CyrusOne’s CHI1 facility house thousands of high-density servers that generate intense heat. Without continuous cooling, servers throttle performance or shut down to prevent damage. Since CME’s core trading engines, data feeds, and order matching systems all rely on these servers, a cooling failure created a domino effect—halting all market activity, not just slowing it.
Was this the first time CME Group had a major outage?
Yes. The last comparable disruption occurred in 2019, when a software bug triggered a 30-minute halt. This 2025 incident—lasting over 13 hours—was the longest and most severe in more than six years, highlighting how physical infrastructure risks have grown even as digital systems have become more sophisticated.
How did the Thanksgiving holiday worsen the impact?
Trading volumes were already at 40% of normal levels due to the holiday, meaning fewer participants were monitoring the market. With thin liquidity, even a short outage caused sharp price gaps when trading resumed. Traders had no way to adjust positions during the halt, leading to increased volatility and risk exposure once markets reopened.
What does this mean for future crypto futures launches?
CME Group planned to launch spot-quoted crypto futures for XRP and Solana on December 15, 2025. The outage has raised regulatory and investor concerns about whether its infrastructure can reliably support the high-frequency, 24/7 trading demands of crypto markets. Regulators may delay approval pending a full infrastructure review.