What happened at M&S on December 27?

The Marks and Spencer hack was a human error that disabled online sales for about six weeks, exposed some customer data, and wiped roughly £324 million of revenue, per media reports. Store trade helped, but interim profits were halved. The incident highlights rising cyber risk across UK retail operations.

How could this affect profits and cash flow?

Fixed costs kept running while online volumes vanished, so margins took a hit. Clearance and promotions can pressure gross margin, while recovery marketing adds expense. Cash conversion typically weakens as orders slip and inventory builds. Normalisation depends on regaining customers and stabilising fulfilment after systems are fully restored.

What should investors watch next?

After the Marks and Spencer hack, focus on outage duration, orders recovered, complaint rates, and markdowns in January updates. Ask for testing, backups, and access control upgrades, plus details on cyber insurance. Clear metrics and timelines build confidence. Any sign of sustained churn or higher service costs would point to lingering damage to earnings.

What is Stuart Machin’s role in the recovery?

Stuart Machin is the M&S chief executive. Investors will look to him for clear communication, targets, and timelines on service levels, security, and online growth. Credible fixes, better uptime, and lower complaints can rebuild trust and support valuation. Vague plans risk prolonging the impact on performance and sentiment.

Global Market Insights

December 27: Marks & Spencer Hack Costs £324m, Profits Halved

ByHuzaifa Zahoor December 27, 2025December 27, 2025

Marks and Spencer hack has become the year’s standout UK retail cyberattack. On December 27, reports said a human error knocked out online sales for six weeks, exposed customer data, and wiped roughly £324 million of revenue, as reported by source. Interim profits were halved, highlighting fragile margins into peak trading. For investors, the incident refocuses attention on resilience, cash conversion, and leadership. We review what happened, the likely profit and cash impacts, how boards can reduce risk, and what questions to ask Stuart Machin and the M&S team next.