A 91.9% plunge announced today in Tesco's first half pre-tax profits extends a miserable run of updates from the supermarket chain. 

Here is a timeline of Tesco's performance since Philip Clarke took the helm in 2011.

February 2011
Terry Leahy steps down as chief executive on his 55th birthday after 14 years in charge, overseeing a leap in pre-tax profits from £750m in 1997 to £3.4 billion at the group's last set of annual figures in April 2010. The market share of the group stands at 30.5%.

January 2012
Less than a year into Mr Clarke's tenure, Tesco shocks the market with its first profit warning in almost 20 years after poor Christmas trading.

Shares plunge by as much as 15%, or more than £4 billion, as it finds itself squeezed by discounters Aldi and Lidl and upmarket Waitrose and Marks & Spencer.

April 2012
Tesco unveils a £1 billion UK revival plan, which includes upgrading stores, the recruitment of more staff and better prices and value. The initiative follows complaints that its 2,800 stores are cold and industrial with poor levels of service.

April 2013
The retailer reports its first fall in annual profits in 19 years, with post-tax profit tumbling almost 96% to £120m from a year earlier. The figure is hit by a £1.2 billion charge on the retailer's US Fresh & Easy chain of around 200 stores as it confirms it will leave the country.

The firm also suffers a £804m write-down in the UK on land for over 100 major stores, bought at the height of the property boom, which will no longer be developed.

February 2014
The supermarket promises to spend an additional £200m 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 retail juggernaut 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 £250m. 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 dodgy numbers as the company suspends a total of eight executives. US investment guru Warren Buffett off-loads his Tesco shares, labelling his investment a "huge mistake". 

When its latest figures are finally published they reveal a 91.9% plunge in first half pre-tax profits to £112m. Tesco also reveals the original overstatement estimate was an understatement - £263m, not £250m. 

The group's chairman Richard Broadbent says he is preparing to step down saying "the issues that have come to light are a matter of profound regret".