As Tesco announces another fall in sales and plans to close 43 stores, here is a timeline of the supermarket giant's performance since 2011.
February 2011: CEO Sir Terry Leahy steps down after 14 years, overseeing a leap in pre-tax profits from £750 million in 1997 to £3.4 billion in April 2010. The market share of the group stands at 30.5%
January 2012: Less than a year into Philip Clarke's tenure, Tesco issues its first profit warning in almost 20 years after poor Christmas trading. Shares drop by as much as 15%, or more than £4 billion
April 2012: Tesco unveils a £1 billion UK revival plan, which includes upgrading stores, recruiting more staff and better prices and value, following complaints that its 2,800 stores are cold and industrial with poor levels of service
January 2013: The horsemeat scandal hits Tesco, along with other food retailers. The supermarket takes out national newspaper adverts to apologise for selling beefburgers containing horsemeat but £300 million is wiped from the retailer's market value
April 2013: The retailer reports its first fall in annual profits in 19 years, with post-tax profit tumbling almost 96% to £120 million from a year earlier. It pulls the plug on its US Fresh & Easy chain of around 200 stores at a cost of £1.2 billion. The firm scraps plans for 100 major new stores, leading to a £804 million property write-down
February 2014: The supermarket promises to spend an additional £200 million on lower prices for basic products, such as carrots, tomatoes, onions, peppers and cucumbers. It will also rein in annual capital spending to no more than £2.5 billion for at least the next three years as a result of the dramatic reduction in store expansion - nearly half the £4.7 billion spent in 2008/09
April 2014: Mr Clarke brushes off speculation about his future despite little sign that his £1 billion plan to turn around the supermarket is bearing fruit. Profits fall 6.9% to £3.05 billion for the year to February 22 while fourth-quarter like-for-like sales slump by 3% as its UK market share falls to 28.6% in the 12 weeks to March 31, from 29.7% in the same period a year earlier
June 2014: Till-roll figures from Kantar Worldpanel show a decline in Tesco's market share to 29% in the 12 weeks to May 25, compared with 30.5% a year earlier. A day later, the chain reports a 3.7% fall in like-for-like sales for the first quarter of its financial year. It is a performance that Mr Clarke admits is the worst he has seen in four decades at the supermarket chain
July 2014: Tesco announces that Mr Clarke will step down from the board on October 1 to be replaced by Unilever executive Dave Lewis. Sales and trading profit in the first half of the year are "somewhat below" expectations, the company adds
August 2014: The change at the top of the supermarket is brought forward by a month in order to allow Mr Lewis to commence a review of "every aspect" of the group's operations. The move comes after the chain reveals another profits warning and slashes its dividend to shareholders by 75%
September 2014: The previous month's guidance turns out to be too optimistic as the company reveals it has overstated profits by £250 million. It asks Deloitte to carry out an investigation into the error, which relates to timing issues on when Tesco's UK business reports the income it receives from suppliers
October 2014: The Financial Conduct Authority launches a probe into the numbers as Tesco suspends eight executives. US investment guru Warren Buffett off-loads his Tesco shares, labelling his investment a "huge mistake". Figures then reveal a 91.9% drop in first half pre-tax profits to £112 million. Tesco also reveals the original overstatement estimate was an understatement - £263 million, not £250 million. The group's chairman Sir Richard Broadbent says he is preparing to step down saying "the issues that have come to light are a matter of profound regret". Days later Tesco is formally placed under criminal investigation by the Serious Fraud Office
December 2014: Dave Lewis spells out the scale of the problems facing Britain's biggest supermarket as it issues a £500 million profits warning. The accounting watchdog the Financial Reporting Council then launches an investigation into the £263 million profits overstatement.
January 2015: Tesco announces it is shutting its head office as well as 43 unprofitable stores as part of a raft of new measures as new boss Dave Lewis battles to turn around the group's fortunes