However, Wednesday's gain of 12.1% paled by comparison with its 66% plunge on Tuesday.
At the other end of the scale, advertising giant WPP's shares sank 11% after it reported slowing sales.
At the close, the FTSE 100 was just in positive territory, up 0.91 points or 0.01% at 7,382.65.
On the currency markets, the pound was down 0.3% against the dollar at $1.2786 and down 0.63% against the euro at 1.031 euros.

Annie Besala Ekofo, 53, and Bervil Kalikaka-Ekofo, 21, were found dead in East Finchley on Thursday.
The Met Police said a 24-year-old man was arrested on Sunday on suspicion of murder and is in custody at a north London police station.
A 20-year-old man held on Saturday has been released on bail until October.
Scotland Yard also revealed Mr Kalikaka-Ekofo had died from a gunshot wound to the head.
A post-mortem examination for the University of West London psychology student took place at Northwick Park Hospital mortuary on Saturday, it said.
A post-mortem examination on Ms Besala is yet to take place.
Detectives earlier launched a fresh appeal for witnesses.
They said there was no evidence to suggest the pair were the intended victims but would be exploring whether anyone else linked to their address could have been a potential target.
Police were called to Elmshurst Crescent by the London Ambulance Service at about 06:25 BST and found the pair in their flat.
Four other people, including a child, were also at the property at the time of the incident but were not harmed.

Baroness Morgan said Labour is in a serious situation if it cannot reconnect with working class communities.
She said there "probably was an element" of Labour's Remain campaign starting too late.
"A lot of us were exhausted", she told BBC Radio Wales.
Senior Welsh Labour sources have privately said they were wary of talking about Brexit before the assembly election in case it drove Eurosceptic supporters towards UKIP.
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Asked if Labour's Remain campaign started too late, she told the Eye on Wales programme: "I think there probably was an element of that.
"And don't forget in Wales we had the assembly elections where people were not talking about the European Union. We were focused absolutely on those assembly elections."
She added: "I think it was a mistake not to be talking about the European referendum in those assembly elections."
Wales voted 52.5% to 47.5% for Brexit. Only five counting areas voted to Remain.
The strongest Leave votes were in Torfaen (60%) and Blaenau Gwent (62%) - two traditional Labour strongholds in the south Wales valleys.
The Welsh government has a programme to "re-energise" communities that voted to Leave, much of which would have been funded by EU money, Baroness Morgan said.
"The question for us now is how on Earth do we reorganise the economy without that European funding?" she asked.
"Unless we find a way to reconnect with that working class element within our communities then I think the Labour party is in a serious situation in future".
Labour won 29 seats at May's assembly election - a better result than many expected - but lost 7.6% of its share of the vote on the constituency ballot.
Earlier, on BBC Sunday Politics Wales, Baroness Morgan said Carwyn Jones was "absolutely, without question" the right man to lead Welsh Labour.
Troubled doorstep lender Provident Financial has gone from being Tuesday's biggest stock market loser to Wednesday's biggest winner.
[NEXT_CONCEPT]
Police probing the fatal shooting of a mother-of-nine and her nephew at their north London flat have arrested two men.
[NEXT_CONCEPT]
It was a mistake for Labour to avoid talking about the EU referendum during the assembly election campaign, one of the party's AMs has said.