Chart: Marks & Spencer cyber attack could have £40m weekly sales impact

The retailer has not been able to make any online sales since Easter weekend due to a cyber attack. With 33% of clothing and home sales taking place online, BofA analysts estimate a weekly impact of £26m. 

But online sales are not the only thing that has been affected at M&S, with in-store sales having also seen some impact. Last week, for example, the retailer had to pause some of its popular meal deal offers. 

An assumption of a 10% disruption to in-store food sales would lead to around £17m more lost in sales per week. 

All this could add up to a sizable short-term dent in profitability. If things are not resolved by the group’s FY25 update on May 21, it would represent the fifth week of disruptions, which we estimate could carry an 8% impact on the group’s FY26 EBIT. 

Despite all this, the note still suggests that any effects are likely to be temporary. “The recent disruption may impact FY26 results in the short term, but is not a reflection of the group’s mid-term plan, which has improved market share and margins,” it said.

M&S confirmed today that personal customer data had been stolen during the cyber attack, potentially including contact details, birth dates and order histories. Importantly, though, they clarified that payment and card details, as well as passwords, had not been affected. 

In a note to customers, chief executive Stuart Machin said that “unfortunately, some personal customer information has been taken”.

“Importantly, there is no evidence that the information has been shared,” he added.

The Co-op, which along with M&S and Harrods, was also targeted in cyber attacks, also confirmed last week that customer data had been affected in the hack. 

“This data includes Co-op Group members’ personal data such as names and contact details, and did not include members’ passwords, bank or credit card details, transactions, or information relating to any members’ or customers’ products or services with The Co-op Group,” the retailer said in a statement on Friday.

Retail Week has reached out to M&S for comment on the BofA figures.