The oversight occurred on 4 December when the unnamed individual replaced large volumes of genuine adverts with a blank yellow rectangle across the US and Australia.
The error persisted for a full 45 minutes before administrators were able to restore settings, but the issue raises significant questions about the efficacy of the search giant’s internal failsafe measures.
According to Google, the mistake occurred when a trainee ‘went further than intended’ when set loose on its ad buying system, placing a live order instead of a dummy one. A far higher value was attached to this advert than other genuine examples, ensuring that it spread like wildfire when placed on multiple third-party exchanges.
In a statement Google said it would reimburse publishers for any losses incurred as a result of the mistake and had put in place measures to prevent a repeat. It said: “As soon as we were made aware of this honest mistake we worked quickly to stop the campaigns running.”
According to The Financial Times, which first broke the story, this error could end up costing Google as much as £7.9m in lost fees and corrective costs to put right.