Microsoft's 12-Hour Outlook and Teams Outage Rattles Business Worldwide

A more than 12-hour outage of Microsoft Outlook and Teams crippled communications for businesses and governments globally on Friday, halting at least one bond repurchase in Europe-era fashion — by fax — and forcing Workhorse Group to push its results to November 16.

Microsoft blamed server issues for the incident, which also knocked out its Copilot AI assistant. The company said a broader rollout of software fixes had started to stabilize the system and that it was not aware of any malicious activity.

Outlook and Teams serve hundreds of millions of users and rank among the most widely used workplace applications on the planet. For most of Friday, people couldn't send emails, manage calendars or host virtual meetings.

What did the outage actually hit?

Microsoft said the disruption specifically affected features tied to Exchange Online, its cloud-based email and scheduling hub. Applications that weren't connected to it kept running. Organizations that host Microsoft services on their own servers — rather than in the cloud — were somewhat spared.

Government agencies from Australia to Japan and the United States felt the impact. Trading firms reported delays. Some companies couldn't publish earnings, and airlines warned customers of communication lags, according to public statements.

In the UK, a government spokesperson said it was working with Microsoft on a fix for organizations including the NHS and London's Metropolitan Police. The outage hit the Met's ability to report some crimes online, though its response to calls was unaffected. NHS local services turned to alternate IT systems and paper records.

Fax machines and canceled trades

For businesses, the fallout was widespread and, in places, oddly retro:

• Euronext, the European exchange operator, reported email disruptions.
• British insurer Aviva activated backups for its earnings calls.
• Danish shipping giant Maersk warned customers of delayed updates.
• Indian airlines IndiGo, Akasa Air and Air India said email support services were impacted.
• OpenAI and Anthropic faced issues with Microsoft connectors.

The financial plumbing took real damage. The outage disrupted fund management at Taiwanese securities firms, life insurers and investment trust companies. One company canceled a bond repurchase transaction, a source familiar with the situation told Reuters. A second Taiwanese financial firm resorted to fax machines to confirm trades, another source said.

Earnings calendars slipped too. US electric truck maker Workhorse Group rescheduled Thursday's results to November 16, while Switzerland's Richemont briefly delayed its first-half results announcement on Friday.

In Australia, where the spy agency and federal police were among the affected organizations, Cyber Security Minister Tony Burke said Microsoft does not suspect a cyber attack. "The impact that they are dealing with … is very much on email systems," the minister said.

What does this change for IT buyers?

This is one of the longest outages in Microsoft's history and the second disruption to its services this year. Microsoft faced 365 outages in January this year and in October last year. Last month, an Azure cloud outage hit its productivity suite and a range of industries worldwide.

"The bigger worry is that this is not the first Microsoft 365 outage this year," said Josh Gilbert, a market analyst at trading platform eToro. "If reliability starts to look like a recurring problem, it hands every IT department a reason to think twice before putting even more of their business in one provider's hands."

Microsoft shares fell 1.7% before the bell, lagging the broader market. They're still up roughly 8% so far this year.

The market reaction suggests investors see this as a bruise, not a break. Some analysts have questioned whether such incidents can actually push customers to rivals, given the steep switching costs of replacing tools embedded so deeply in daily operations. That's the real so-what: the incident deepens questions about global reliance on a handful of Big Tech companies that supply both the essential software and the cloud infrastructure underneath it — and until switching costs fall, that concentration risk stays put.