Trading was halted across much of the Chicago Mercantile Exchange early Friday with the group blaming a "cooling issue" at a partner's data center.

When a data center cooling issue halted futures and options trading at the Chicago Mercantile Exchange, it focused attention on the hidden infrastructure that’s becoming ever more critical to daily life: data centers.

A cooling failure at CME Group’s primary Aurora data center halted futures trading worldwide, raising questions about safeguards and private-equity ownership.

The outage, which lasted for 10 hours, hit CME’s equity, bond and commodity futures. It also offered a warning.

The Aurora, Illinois, complex has served as the primary hub of digital operations for the world’s largest futures exchange operator CME Group Inc. for nearly two decades. Traders want to be close to the data center to reduce latency,

One of the first signs of trouble arrived at 9:41 p.m. Eastern time on Thursday, when most of Wall Street was shut and traders were still enjoying the Thanksgiving holiday in the US.