Microsoft Outage Pushes Traders Back to WhatsApp, Phone and Fax

By Tom Whitfield

A Microsoft outage running past 15 hours forced market operators to execute deals by phone, WhatsApp and even fax machines, after the failure disrupted communications at stock exchanges and financial firms across more than 70 countries, including Brazil. The cause has not been identified. The blackout hits Outlook, Copilot and Teams, the Microsoft services that depend on the cloud.

How far did the disruption reach?

In Singapore, operators reported that some banks could not complete financing operations. Euronext, Nasdaq and the German exchange all reported problems with their email services. Japanese firms said trades were being settled by fax. Indian brokers warned that responses to queries sent via Outlook could be delayed.

Kenneth Goh, a private wealth management director at broker UOB Kay Hian, lost access to the market updates that inform his recommendations to high-net-worth clients while travelling on business in Malaysia. He relied on unstable phone lines to speak with clients.

"It has been extremely irritating," Goh said. "If the outage goes past 24 hours, we'll enter a danger zone."

Which companies were caught out?

The outage ranks among Microsoft's most serious service interruptions of recent times. It disrupted workflows on trading desks and delayed the release of corporate information. Richemont, the owner of Cartier, briefly postponed the publication of its financial results because of the failure.

Microsoft said it was observing "positive signs of server stability", but services had not yet been restored. Trading on global markets proceeded relatively calmly: S&P 500 futures, the benchmark New York exchange index, held practically steady.

What happened behind the scenes at trading desks?

Ryutaro Kimura, senior fixed-income strategist at BNP Paribas Asset Management in Tokyo, said that while trading itself was little affected, "trade confirmations piled up, creating problems for the back-office teams responsible for settling the deals".

"The trading desks continued closing deals by phone and fax," Kimura said.

Traders at CMC Markets turned to what one described as old-fashioned methods after Microsoft's systems went down.

"Everybody went back to using the phone, and our WhatsApp conversations got busier than normal," said Eugene Koh, a trader in CMC Markets' commercial area in Singapore.

What comes next?

The episode lays bare how tightly the global financial workflow is bound to a single vendor's cloud stack. Email, chat and AI copilot tools sit on the same infrastructure, and when that infrastructure fails, exchanges, banks and brokers lose their primary channels at once.

If the outage passes the 24-hour mark, as Goh warned, settlement backlogs will deepen and delayed corporate disclosures could stack up. Firms that rehearsed analogue fallbacks — phones, faxes, consumer messaging apps — kept trading through the failure. Those that did not now have a clear case, written in lost hours, for building redundancy into their communications stack.