The five billion euros man, Jérôme Kerviel, stepped involuntarily out of the shadows yesterday, 12 months after he became the most talked about, and sought after, man on the planet. In a lengthy newspaper interview – which he later contested – the alleged rogue trader gave his first extensive public explanation of how he came to lose almost €5bn for the French bank, Société Générale.

M. Kerviel, 32, was quoted as saying that he had taken "orgasmic pleasure" in making "astronomic" bets on financial markets. He said that he had lost "all sense of reality" but that his initial, enormous trading successes had been approved by bank chiefs. His superiors had, he said, called him "the cash machine". They only started to challenge the "crazy risks" he was taking when he began to lose money early last year.

M. Kerviel admitted that he had been briefly racked by guilt when he hit the trading "jackpot" on the day that terrorist bombs exploded in London in July 2005. "I made €500,000 in a few seconds... I was jubilant. Suddenly I realised that I was having fun because people had been hurt by bombs. I ran to the toilet and vomited."

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Something similar happened on the day of the 9/11 attacks in New York, he said. On that day, Soc Gen had made "colossal" trading gains – the highest in its history.

Despite his "moment of weakness" in July 2005, the young trader went on to bet huge, unauthorised sums on the ups and downs of European stock markets – mostly the downs – for another two and a half years.

In a radio interview yesterday morning, M. Kerviel claimed that he had given no formal interview to the newspaper Le Parisien. He said that the remarks published in the newspaper had been made in private and that the published extracts had been "shoved together" and "taken out of context".

One of his four-strong team of lawyers admitted later, however, that the interview – actually based on six interviews – was genuine and accurate. He said that M. Kerviel had reacted angrily because the article had been published, without prior agreement, on the day that he was to be questioned for a final time by investigating magistrates.

The former trader's fury may have been fuelled by the fact that the newspaper quoted him as making an attack on the magistrates themselves. M. Kerviel accused them of consistently rejecting his side of the story and accepting the bank's argument that it was merely the innocent victim of a malicious act of financial "terrorism".

"I have the impression that this has been an investigation sponsored by Société Générale," M. Kerviel said.

Under French law, investigating magistrates are required to examine the evidence both "for and against" the guilt of a suspect. The magistrates investigating the Kerviel case are expected to recommend in the next couple of weeks that he should be prosecuted for breach of trust, falsifying documents and hacking into the bank's computers to cover his tracks. A possible charge of fraud was dropped last January because the magistrates accepted that M. Kerviel had never attempted to embezzle a centime of the billions of euros that passed across his computer screen.

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The trial is, however, not expected to take place before the end of this year or early in 2010.

M. Kerviel has become something of a cult hero since his activities were revealed 12 months ago tomorrow. He has a fan club. He been the protagonist of a comic book. His story is to be made into a film.

His heroic stature has, if anything, been enhanced since the risky and complex investments of most financial institutions worldwide plunged the globe into recession. M. Kerviel is being portrayed by his fans – and by his legal team – as a mere ant or foot-soldier in a much larger frenzy of banking speculation which was encouraged from the highest level.

One of his four lawyers, Maître Eric Dupond-Moretti, said after yesterday's interrogation by magistrates that M. Kerviel had been abandoned by his bosses like "rats leaving a sinking ship".

"Kerviel is not a victim. He admits a certain number of things," Maître Dupond-Moretti said. "But the mechanism of control did not function at Société Générale" because the bank also "knew a certain number of things". "It's a bit rich to leave Kerviel all alone as the sole person responsible for the losses of Société Générale, for the global credit crisis, for the sub-prime problem – for everything that we now know about," the lawyer said.

On 24 January last year, Société Générale stunned the world when it announced that it had lost about €4.9bn because of what it insisted were unauthorised trades by M. Kerviel on the futures market for European share prices. The young trader immediately admitted to investigators that he had made enormous bets on the downward movement of shares but insisted that his superiors knew and had turned a blind eye – so long as he was winning.

In the remarks attributed to him by Le Parisien yesterday, the ex-trader told essentially the same story but in much more detail than ever before.

He admitted taking "crazy risks" and becoming obsessed with winning, as if he was "playing a computer game". He had, he said, "obstinately" refused to grasp that the trend of the market had turned against him in early 2008. "For a normal trader, a gain of €30,000 to €40,000 was a good day... For me, €1m was a rubbish day... I made astronomical gains which gave me, sometimes, an orgasmic pleasure," he said.

By the end of 2007, he said, he had made a €1.7bn profit, which, he claimed, the bank had used to cover the losses of some of his colleagues. "Everyone came and got stuck in [to his earnings] to refinance themselves," he said. "When I hear them say today that they knew nothing, I really think I am at the hypocrites' ball."

Of the day of the London bombings, in July 2005, he said that he had made huge bets on a fall in the shares of insurance companies, especially the big German company Allianz. When news came in of the terrorist attacks in London, the stock markets fell and "everyone began to lose money except me". Realising that he was profiting from death and injury, he said, he fled to the toilet to throw up. "But this attack of weakness didn't last long and I went back to the trading floor and started working again."

He told a superior what had happened to him. The boss made a macabre revelation. He told M. Kerviel that 9/11 – the day of the terror attacks on New York in 2002 – had been "the best day's trading in the history of Société Générale. That day, it seems, their gains were colossal."

M. Kerviel said his superiors would not query his positions but they would come to him and say: "Hey, cash-machine, how much did you earn today?"

M. Kerviel said it was "absurd" for Société Générale to claim that they were kept in the dark. "In 2007, when I made a trade from a collegue's work station and made €500,000, I gave them a completely stupid explanation. Something surreal. They should never have believed me. They said nothing... It was as if I was driving a jet-powered Ferrari. For 365 laps, I overtake everyone else at 3,000kph. And they saw nothing. They said nothing is that credible?"

M. Kerviel is now living in a suburb of Paris and works for a computer company which belongs to a friend. He said that he had received several job offers from investment funds and still had a hankering to go back to the trading floor. "I look at what's happening in the stock markets and I say 'that's what everyone should be doing'."

M. Kerviel said that his dearest wish now was to return to obscurity. He said that his obsessive behaviour as a banker had destroyed his relationship with a girl-friend and distanced him from his mother. But he said that he and his mother had become "much closer again" since he was arrested last year. "If I had a bit of money," he said, "I would go off with my mum for a holiday so she could calm down a bit."