M&S has blamed unseasonal autumn weather as it reported a 2.8% fall in like-for-like sales for its clothing and home division over the Christmas quarter.
The retailer also said food sales were down, by 0.4%, for the 13 weeks to 30 December – though both figures were slightly better than the City had expected.
Shares opened 2% lower.
Its figures were released at the same time as rival John Lewis, which reported a 3.1% rise in like-for-like sales for the six weeks to 30 December.
But Sir Charlie Mayfield, chairman of the partnership which owns the department store chain as well as supermarket Waitrose, admitted that pressure on profit margins had intensified amid rising costs thanks to the pound’s Brexit-related weakness, and warned that trading would remain “volatile” for the year ahead.
Elsewhere, House of Fraser said sales in the six weeks to 23 December were down 2.9% and post-Christmas performance was “disappointing”.
M&S chief executive Steve Rowe said it had seen revenue grow both in-store and online in the weeks leading up to Christmas while it maintained its full-price stance in a “very promotional market” and did not participate in the Black Friday discount day.
“However, the impact of an unseasonal October resulted in an overall revenue decline,” said Mr Rowe. “As a result, we carried more stock into the December sale.”
The update highlighted just how dependent clothing retailers can be on the weather, with milder autumns and winters tending to dampen demand for higher-price items such as warm coats and knitwear.
It comes after rival Next said it had seen a better-than-expected Christmas sales performance, partly thanks to cold weather in December – but over a period that did not include October.
Thursday’s slew of trading updates also appeared to suggest a victory for Moz the Monster, John Lewis’s ad campaign star, over Paddington bear – who featured in M&S’s marketing.
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However the figures released by the two retailers were not directly comparable as John Lewis’s covered a shorter period.