A massive Microsoft 365 outage left companies and government agencies around the world without work email for more than 12 hours.
Banks, brokers, and officials had to fall back on phones, paper, and even fax machines. The incident exposed the critical dependence of global financial infrastructure on a single cloud provider.
What happened to Microsoft services
The problems began on Thursday toward evening European time. There were disruptions with access to Exchange Online mailboxes — the Microsoft 365 email system on which many other services depend. Mailboxes periodically failed to open, and emails arrived late or not at all. The outages also affected Teams and the Copilot AI assistant.
Within an hour, complaints had come in from 74 countries and territories. In the US, reports of problems peaked at more than 130,000. More than 430 million people use Microsoft 365 applications.
Microsoft initially attributed the outage to increased load, but then changed its account. Some servers unexpectedly became unavailable, and the remaining infrastructure could not cope. There are no signs of a cyberattack. No timeline for full recovery has been given.
Faxes, paper, and jokes about Microsoft 364
The most unusual consequence was the return of fax machines in Japan. Emails confirming trades stopped working there, and brokerage and asset management companies switched to tools from the last century. Some investment fund settlement prices were published late.
There were enough oddities in other countries as well:
- Japanese officials worked with printouts — Chief Cabinet Deputy Secretary-General Masanao Ozaki reported the outage in the government's shared IT infrastructure;
- CMC Markets traders in Singapore were forced to communicate by phone;
- Morgan Stanley and Goldman Sachs employees in Hong Kong sat for hours without email and Teams;
- Swiss holding Richemont, the owner of Cartier, delayed the publication of its half-year financial statements;
- Japanese carrier Sagawa Express suspended same-day locker reservations;
- OpenAI and Anthropic reported errors in the connectors through which ChatGPT and Claude access email and calendars.
People joked online that Microsoft 365 had turned into Microsoft 364 overnight. The company promises business customers 99.9% availability per month, which is about 43 minutes of downtime. That limit has been exceeded many times over.
Japanese broker SBI FX Trade warned clients that Outlook users might not receive login emails and trade execution notifications, and advised them to check everything directly in the trading terminal. Banks Standard Chartered and ING asked clients to be cautious about calls from "tech support" and suspicious links. Scammers may exploit the outage to steal passwords and one-time codes.
Cryptalist analysis: The incident demonstrates the systemic risk of concentrating critical infrastructure in the hands of a single cloud provider: a single point of failure can paralyze settlement, reporting, and communications across entire markets. For institutional participants, this is a signal to diversify cloud services and revisit business continuity plans, and for the market, it is a reminder that operational risks remain an underestimated factor alongside volatility.