UK retailer John Lewis is writing down property assets it no longer plans to develop for its upmarket grocer Waitrose and investing in technology, logistics and pay as it responds to shifting shopping habits.
John Lewis said Britain's vote to leave the European Union had little noticeable impact on sales so far.
But it added that the full impact of Brexit was not yet clear and it expected "trading pressures" to continue into 2017.
As it responds to big changes in retail, John Lewis said it had decided to prioritise investment in technology, its distribution network and pay, while focusing on sprucing up existing Waitrose stores rather than opening new ones.
Property writedowns caused an exceptional charge of £25m that pushed first-half pretax profit down 74.6%to £56.9m. Excluding the charge, pretax profit fell 14.7% to £81.9m.
Other UK supermarkets such as Tesco and Sainsbury's have also made property writedowns as they closed some stores and halted plans to open others as consumers switch from big weekly shops at out-of-town hypermarkets to buying more online and locally.
Waitrose's premium offering has helped it gain market share as other British supermarkets have lost out to the rise of discounters Aldi and Lidl, which has pushed prices down across the sector.
However, Aldi has now overtaken Waitrose as Britain's sixth-biggest grocer and its market share has slipped slightly in recent months to 5.1%.
John Lewis said like-for-like sales at Waitrose fell by 1% in the first half, while grocery sales online rose 4.3%.
For the first six weeks of the second half from August 1, Waitrose gross sales rose a like-for-like 1.4%.
John Lewis said Waitrose plans more in-store cafes, bakeries, wine and juice bars after "hospitality" sales rose 7.1% in the first half.
It will also invest more in the Waitrose 1 premium range, which saw sales up 19.4%.
As Britain's leading department store business seeks to keep pace with online rivals such as Amazon, John Lewis said investment in technology and distribution now represented 55% of total capital spending, up from 48% last year.
Department store sales rose a like for like 3.1% in the first half, but growth slowed to 0.7% in the first six weeks of the second half.