This week all eyes will turn to first-quarter updates from BP and Royal Dutch Shell and full-year figures from leisure group Whitbread. Oil majors BP and Royal Dutch Shell are both likely to see their first-quarter profits severely dented by sharply falling oil prices.

A year ago, the pair reported Q1 results on the same day and fuelled motorist anger over rising petrol prices by revealing a combined surplus of more than £7bn. But in 2009 the climate is far different, with crude prices below $50 a barrel and set to stay at these levels for much of the year amid a global slowdown.

This compares with last year when crude prices were well above $100 a barrel and heading toward a July peak of $147. According to a consensus of broker forecasts, BP is expected to post "clean" underlying profits of £1.53bn on Tuesday – around two-thirds lower than last year's £4.29bn.

Panmure Gordon's Peter Hitchens said: "The company is starting to get back to growth after a few testing years. Unfortunately this has emerged as it is suffering from the downturn in the operating environment."

Low oil prices could also threaten dividend payments unless the firm adds to debts. But prices are currently at the lower end of the $50 to $60 a barrel break-even point suggested by BP in February's annual results.

Rival Royal Dutch Shell, which reports on Wednesday, is also likely to see underlying Q1 profits well below the £5.39bn seen last year, at £1.8bn.

Shell reported record profits of £22bn for 2008, up 14% on the previous year despite the slumping oil prices at the end of last year.

The firm has also pledged to maintain net investment at near to last year's level of £22.5bn in order to safeguard future profitability.

Analysts will be scouring quarterly figures from satellite broadcaster BSkyB on Wednesday for any signs of slowing growth in customer numbers, as well as for increased customer 'churn', or turnover. Also of interest will be the early response to BSkyB's January initiative to slash the cost of the take-up of its Sky Plus HD service, which combines a personal video recorder with high-definition TV. It has reduced the price of the box to £49 and said anticipated demand meant it would create 1,000 jobs in customer service and installation. Analysts expect pre-tax profits to be down from £192m to £180m this year.

The owner of the Homebase and Argos chains is expected to post sharply reduced underlying pre-tax profits when it reports final results on Wednesday. Analysts predict Home Retail will reveal profits have slumped by around a quarter to £320m from £433m last year.

The company has already said it is on track to meet market expectations for profits in the financial year to the end of February.

Strong results from Amazon UK and video games firm Game Group have set high expectations for retailer HMV's trading update, due on Wednesday. Music sales were a strong growth driver, after downloads from its new MP3 store exceeded five million tracks.

HMV, which also owns the Waterstone's book chain, said earlier this year that the music division had enjoyed its best ever Christmas, helping lift like-for-like sales by 3% in HMV UK and Ireland over the festive period. It may provide some further detail on plans to enter the world of live music.