More on those supermarket trading figures from Kantar Worldpanel. Retail expert Steve Dresser tweets:
Tesco, Sainsbury's and Morrisons all lost market share in the 12 weeks to 2 December, according to data from Kantar Worldpanel.
Tesco's market share dipped to 27.6% compared to 28.2% this time last year. Sainsbury's share fell from 16.4% to 16% and Morrisons edged lower from 10.6% to 10.5%.
Asda was the only one of the big four to maintain its position with 15% of the UK grocery market.
The Cooperative gained market share as did the German retailers Aldi and Lidl.
Tesco shares are leading the FTSE 100 higher with a 5% gain.
Probably helping are a couple of positive comments from analysts in the City.
Analysts at Exane BNP Paribas think that profit margins could improve.
And a UBS analyst says there is a "decent possibility" that Tesco might buyback shares next year.
Investors might also have been sniffing a bargain - since August Tesco shares have fallen by around a quarter.
BBC Radio 4
More from Ross Dixon a partner at Hickman and Rose, and solicitor for Chris Bush - the former UK managing director of Tesco.
"My client has had to undergo four years of a really horrendous ordeal, that has come to an end - the right outcome has happened."
"But if the SFO behave in the same way in the future then there is a real risk out there that there will be people running companies where something has going wrong and they will find themselves on trial even though they knew nothing about it."
BBC Radio 4
The Serious Fraud Office is under pressure after its case against two former Tesco directors collapsed.
Ross Dixon is a partner at Hickman and Rose and solicitor for one of the defendants Chris Bush (pictured), the former UK managing director of Tesco.
"For a case of this seriousness and magnitude you would expect the Serious Fraud Office would have sufficient evidence for the case to get to the jury."
"That really thows up questions for the SFO as to what they were doing prosecuting these two men in the first place."
"A lot of the evidence focused on these two men and not really about what was, and what wasn't, going on further down in Tesco."
Richard Sallybanks, partner at BCL Solicitors who represented former UK food commercial director John Scouler in the Tesco trial, says the Serious Fraud Office's prosecution was "fundamentally flawed".
Mr Sallybanks says Mr Scouler should not have been charged, and that the SFO should not have proceeded with the trial.
"Mr Scouler has maintained since the outset of this investigation that he was not guilty of fraud and false accounting, and those close to him always knew that to be the case.
"This is a very significant defeat for the SFO - and a notable win for BCL Solicitors and the two ex Tesco directors," he says.
Business correspondent, BBC News
The collapse of the Tesco trial has put the Serious Fraud Office under scrutiny.
The key witness was Amit Soni, a Tesco senior accountant. He was described as a "whistleblower" who co-commissioned an internal report to expose the gap in the accounts.
The prosecution claimed that when the resulting document landed on the desk of new chief executive Dave Lewis, it was like a hand grenade had gone off in the company.
However, when questioned by the defence, Mr Soni accepted that he had been unaware of improper accounting until he produced his report, which was written months after the problems were already spiralling out of control.
The defence argued that Mr Soni was not a whistleblower at all.
"If Mr Soni didn't know the accounts were unreliable, then how on earth was Mr Bush supposed to know that they were", his barrister, Adrian Darbishire QC, told the jury.
More on the Tesco case.
Chris Bush, ex-UK managing director, and John Scouler, ex-UK food commercial director, were accused of manipulating figures that resulted in Tesco's profits being massively overstated.
In August 2014, Tesco said it expected half-year profits to be about £1.1bn.
However, weeks later, it said profits had been overstated by about £250m.
Both men had denied the charges.