Marks & Spencer Group Plc posted a 55.4% drop in first-half adjusted pre-tax profit on Wednesday as it took a hit from a recent cyber attack.
In the 26 weeks to 27 September, adjusted pre-tax profit declined to £184.1m from £413.1m in the same period a year earlier.
The retailer pointed to a £101.6m charge in relation to the incident, with further charges of around £34m expected in the second half of the year, taking total costs to about £136m. In May, it estimated that the incident would cost it about £300m in operating profits for the year.
M&S also said it had claimed £100m from insurance for the cyber attack.
Sales during the period rose 22.1% to £8bn, driven by the consolidation of Ocado Retail Limited, which generated revenue of £1.5bn.
Chief executive Stuart Machin said: "The first half of this year was an extraordinary moment in time for M&S. However, the underlying strength of our business and robust financial foundations gave us the resilience to face into the challenge and deal with it. We are now getting back on track. Change, on the other hand, is not a moment. Change is constant and that is why we are resolute in our ambition to reshape M&S for growth.
"In the second half, we expect profit to be at least in line with last year. This should give us a springboard into the new financial year and set M&S up for further growth. The retail sector is facing significant headwinds - in the first half, cost increases from new taxes were over £50m - but there is much within our control and accelerating our cost reduction programme will help to mitigate this .
"Our plan to reshape M&S for long -term sustainable growth is unchanged, our ambitions are undimmed, and our determination to knuckle down and deliver is stronger than ever. To date we have achieved meaningful progress, but what's exciting is that there is so much more to do and so much opportunity ahead of us."