British businesses face a “bad day for UK plc productivity” thanks to Microsoft’s global outage, prompting warnings of mounting financial losses and the risks of relying on a single technology provider.

The disruption, which began on Thursday evening, has left companies struggling to access Outlook, Teams and other Microsoft 365 services, affecting everything from customer communications to financial transactions.

Supermarket giant Asda reported problems with online customer registrations, password resets and email changes, although understands its operations have been restored.

Rail operators were also hit, with Great Western Railway warning passengers that emailed ticket confirmations were unavailable and advising customers to access tickets through its app or website.

The disruption has also affected financial services firms, including Natwest, as businesses across the City grapple with communication failures.

Riz Malik, an independent financial adviser at R3 Wealth, said: “Friday the 13th spells doom for Microsoft and many of those that rely on their services. This is a bad day for UK plc productivity.”

Businesses warn of mounting losses from Microsoft outage

The outage has raised concerns over the financial cost of prolonged disruption, particularly for smaller businesses that rely on Microsoft’s software to communicate with customers, suppliers and lenders.

Samuel Mather-Holgate, managing director of Mather and Murray Financial, warned that the disruption could become one of the “most economically damaging technology failures in history” and cost businesses billions.

The impact has been particularly acute for time-sensitive transactions, including property purchases, where delays in exchanging documents between solicitors, lenders and brokers can hold up completions.

Financial services firms also face heightened pressure to maintain access to critical information, with regulators requiring businesses to demonstrate that they can withstand major technology disruptions.

Rob Mason, director of regulatory intelligence at Global Relay, said firms could not afford to “go dark”, warning that the outage would prompt fresh questions about operational resilience and dependence on third-party providers.

The disruption has also exposed the extent to which British companies rely on a small number of American technology giants for their day-to-day operations.

Microsoft and Amazon Web Services together control an estimated 70 to 80 per cent of the UK’s public cloud market, leaving businesses heavily exposed to failures at major providers.

Mark Boost, chief executive of UK cloud provider Civo, said the concentration of services within a handful of companies meant a single outage could disrupt multiple business functions simultaneously.

“When the same company runs the cloud, email, documents and collaboration tools, a single failure takes everything down together,” he said.

However, Microsoft’s entrenched position means businesses are unlikely to abandon its services overnight.

Amish Patel, head of equity research at Raymond James, said the direct financial impact on Microsoft was likely to be negligible, given its scale and the difficulty customers face in switching providers.

“The more interesting question is whether repeated outages begin to change how businesses think about their dependence on a single technology provider,” he said.

Microsoft said on Friday that it was making “additional progress toward service recovery”, with traffic gradually being restored after disruption spread across 74 countries.

The company attributed the problems to servers becoming unexpectedly unavailable and said there was no evidence of a cyberattack.