Confectioner Ferrero has been cleared of allegations of fraud relating to the supply of hazelnuts.
The case arose after two banks lent 22.8m euros ($40.4m; £24.5m) to a Turkish firm that was the world's biggest hazelnut supplier at the time.
The firm, Baskan Gida, used the money to buy hazelnuts, but then transferred them to a second company, which meant the banks did not get their money back.
The banks had alleged that Ferrero had been involved in the switch.
But the judge Mr Justice Briggs did not agree with the case, which was brought by Bank of Tokyo Mitsubishi and KBC Bank, and cleared Ferrero, the company behind Ferrero Rocher chocolates as well as Nutella spread and Tic-tacs.
Mr Briggs handed down a 272-page judgment describing the trial as being "very long and no doubt enormously expensive".
The judge ruled that another defendant, Shabbir Abidali, had been involved in the conspiracy.
There will be another hearing at the end of the month to decide how much Mr Abidali will have to pay, although the judge said he would not be liable for the full 22.8m euros.
The hearing will also decide who will have to pay the costs of the case.
The case has been going on for seven years and has been in court for a total of 84 days since October, so the costs are expected to be greater than the 22.8m euros the banks lost in the first place.
A parallel trial going on Italy recently estimated that Ferrer's total costs, including the trial in London, could be around 11m euros.
The banks and Mr Abidali will also have to decide whether they want to appeal against the judgement.
Turkey grows 70% to 75% of the world's hazelnuts
The judge decided that three Ferrero witnesses - Antonio Do, Rosa Brunet and Alessio Casale - had all deliberately lied to the court.
Mr Brunet has now retired and the other two are still working for Ferrero.
Mr Briggs decided that they had lied about certain aspects of Ferrero's relationship with Baskan Gida, to protect the reputation of Ferrero, but he decided that did not mean that Ferrero had been trying to defraud the banks.
But the company defended its employees.
"Ferrero remains of the view that all of its personnel acted properly and with integrity throughout," said its solicitor Andrew Howell of Barlow Lyde & Gilbert.
The judge also said that Mr Abidali was "not an honest man", having created and backdated documents "which were plainly designed to give a false and misleading impression".
Mr Abidali's solicitors, Steptoe & Johnson, said: "Our client's position is that he has acted honestly and in good faith throughout."
As for the members of the Baskan family in Turkey that owned Baskan Gida, the judge ruled that they had indeed successfully defrauded the banks.
They were named as defendants in the case, but did not turn up at any of the proceedings and the judge concluded that they had probably not managed to make enough money out of the fraud to be worth pursuing through the Turkish legal system.
"Even if a judgment in these proceedings could be enforced against them in Turkey, it is unlikely that any of them are worth powder and shot," he said.
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