For the year to 10 July the company filed a trading loss of£1.3 million. A 3.1 per cent fall in sales was attributable to a number of factors, said the retailer.
The sales decline resulted partly from the closure of certain departments ahead of the£24 million refurbishment of the Piccadilly store in London, which begins early next year.
Additionally, investments in product development, brand packaging and a new web site (Fortnumandmason.co.uk) have pushed the year's results into the red.
Commenting on the first figures since her appointment as managing director, Beverley Aspinall said: 'We have entered a period of change designed to equip Fortnum & Mason for the future and this exciting vision requires high levels of focus and investment.
'We have completed an in-depth review of the business and we are positioning Fortnum & Mason as a fountain of ideas for food, wine, celebration and entertainment for those who seek the very best.'