The squeeze on Britain’s established supermarkets will be highlighted this week, with Tesco, the sector’s biggest player, expected to report another decline in annual profits on Wednesday.

On Tuesday, department stores group Debenhams publishes half-year results, months after issuing a stark profits warning when a hoped-for surge in Christmas sales failed to materialise.

Margins were lower partly because the company cut prices in order to compete amid an unprecedented wave of promotions on the high street.

However, these failed to entice the numbers expected, with like-for-like sales rising only by a paper-thin 0.1% in the 17 weeks to December 28, meaning more reductions were needed to clear stock in the new year.

Pre-tax profits are now expected to slump by 29% to £85million when interim results are announced.

The group has also been rocked by the resignation of finance boss Simon Herrick, who announced he was to quit days after the profits warning.

It followed reports that Mr Herrick was under pressure amid shareholder concern over his performance. He was criticised over a so-called “Santa tax” letter hitting suppliers with demands for discounts days before Christmas. The group is still searching for a replacement chief financial officer.

JD Sports Fashion is expected to unveil a steep rise in profits when it announces annual results on Tuesday.

The group’s most recent trading update in January cheered City analysts, revealing a strong performance for its sportswear stores over Christmas. Pre-tax profits are expected to rise 29% to about £71m.

The group, which has more than 800 outlets in four countries, revealed earlier this year that like-for-like sales at its core business in the 48 weeks to January 4 were marginally better than the 5.8% reported in November.

It hailed stronger Christmas sales for its sports stores and said that margins were largely protected despite widespread discounting on the high street.

The group also includes other brands it has been trying to improve - outdoor stores under the Blacks and Millets fascias and the fashion outlets Bank and Scotts.

Chairman Peter Cowgill has said that he expects “considerable progress” this year as the company looks to continue the turnaround of its outdoor fascias and improve the performance of the loss-making fashion stores.

In the first half of the financial year, Millets dragged on the group’s soaring profits following its decision not to scrap the chain.

JD had planned to merge the business with Blacks after it bought both brands out of administration but changed its mind and decided to keep Millets going, saving a number of stores.

Tesco is set to reveal a second consecutive year of falling profits on Wednesday, piling further pressure on embattled chief executive Philip Clarke.

Latest industry figures showed that Britain’s biggest supermarket saw its market share fall to 28.6% in the 12 weeks to March 31, from 29.7% a year earlier.

Analysts on average expect to see underlying pre-tax profits at the group shrink by 15% to around £3billion for the full year.

Mr Clarke is in the midst of a £1bn turnaround plan which was launched in the face of last year’s first fall in group profits in nearly 20 years.

Tesco has been retrenching from loss-making international businesses to focus recovery efforts on the UK, where it is scrapping more than 100 major store developments and focusing growth on convenience stores and online.

It is also looking to transform stores into family-friendly retail destinations with the addition of the Giraffe restaurant chain alongside larger stores.

Last week, it emerged that finance director Laurie McIlwee is to step down after 14 years with the company amid reports that he had lost faith in his boss’s strategy to turn around the company’s performance.

Mr McIlwee said he would stay on until a successor was found but warned that Tesco faced a period of “unprecedented change” in the supermarket industry.

Tesco and its “big four” rivals are seeing their market shares eroded by discounters Aldi and Lidl in what Morrisons chief executive Dalton Philips believes is the biggest structural shift in the grocery sector since the 1950s.

Tesco, Asda and Morrisons have all pledged price-cutting strategies to take on the newer rivals, with Sainsbury’s also showing signs of coming under pressure.

Tesco’s last trading update revealed that like-for-like sales fell by 2.4% over the Christmas and New Year period, and Hargreaves Lansdown analyst Keith Bowman said a 2% decline was expected for the fourth quarter to February.

Analysts at Deutsche Bank said it was too early for recent initiatives to have had an impact, pencilling a quarterly sales declined worsening to 2.7%.

FTSE 100 house builder Persimmon updates the City on its recent performance on Wednesday in the wake of jitters over the sector that have put pressure on shares.

There has been speculation that lenders are planning to rein in mortgage approvals due to fears of a housing bubble.

Like other builders, the company has been buoyed by the boost for the housing market provided by the Government’s Help to Buy scheme.

Latest figures from Halifax showed house prices lifted by 8.7% annually in March and that they are continuing to rise at their strongest yearly pace since 2007.

Annual results published in February showed Persimmon’s earnings had surged by nearly 50% last year, as it revealed 2014 had also got off to a good start.

The company, which also includes the Charles Church and Westbury Partnerships brands, said the property market revival had sent pre-tax profits up by a better-than-expected 49% to £330m in 2013, spurred on by initiatives such as Help to Buy.

But Goldman Sachs has taken Persimmon off its “conviction buy” list after reviewing its strategy on builders following their strong run, though it says prospects for the industry look bright and that Persimmon remains a “buy”.

Meanwhile, UBS has upgraded the stock to “buy”, arguing that a high valuation is justified by strong growth and returns.

Analysts at Deutsche Bank said the interim management statement, which is being published on the same day as Persimmon’s annual general meeting, was likely to show a continuation of the strong selling rate reported in its last update.