Business Insider:

Google’s DoubleClick ad server for publishers (DFP) went down for over an hour today, potentially costing publishers across the world millions of dollars in missed advertising revenue as Google scrambled to solve the problem.

Brian O’Kelley, co-founder and CEO of AppNexus, the world’s largest independent ad tech company told Business Insider could have cost publishers, collectively, “$1 million per hour” in lost ad revenue.

This is the server that serves up ads for the Wall Street Journal, Forbes, BBC.com, The Guardian, lots of other big names. Big money at risk here, bad day for folks at DoubleClick.