Former Goldman Sachs bond trader Fabrice Tourre, known as ‘Fabulous Fab, ’ arrives at the Manhattan Federal Court in New York July 24. (Eduardo Munoz/Reuters)

It was the nickname — “Fabulous Fab” — and the boastful e-mails that helped make Fabrice Tourre a symbol of Wall Street’s excess during the financial crisis.

But on Thursday, during his trial for allegedly defrauding investors in a complex scheme based on shabby mortgages, Tourre was downright sheepish about his notorious image.

In perhaps the most widely quoted e-mail presented as evidence against him, Tourre — a Goldman Sachs trader — was boasting to histhen-girlfriend about the deteriorating housing market and the financial products he was devising to make money off of it.

“More and more leverage in the system, the entire system is about to crumble at any moment. . . . The only potential survivor, the fabulous Fab (as Mitch would kindly call me, even though there is nothing fabulous abt me . . .), standing in the middle of all these complex, highly levered, exotic trades he created without necessarily understanding all of the implications of those monstruosities!!! [sic],” the 2007 e-mail said.

On Thursday, Tourre said the note was a “silly, romantic e-mail” written during a time of great market volatility. But he said he “did not create a monstrosity.”

The government seized on Tourre’s personal and professional e-mails to cast the 34-year-old French native as a greedy Wall Street executive who raked in a $1.7 million salary in 2007 by luring investors into a deal that was secretly designed to fail. The mortgage product tanked when the housing market soured, and some investors lost $1 billion.

In another e-mail, dated June 13, 2007, Tourre tells his girlfriend that he’s landed in Belgium and sold some of the deal’s bonds “to widows and orphans that I ran into at the airport.” On Thursday, Tourre said the e-mail was in “bad taste.”

“This is a very silly e-mail I deeply regret,” he said, adding that the real investors were large institutions.

The SEC’s portrayal, during Tourre’s first full day of testimony before a Manhattan jury, contrasted sharply with the defense team’s narrative of a man who never aspired to work on Wall Street and grew up in a small French town with a father who sold furniture and a mother who did pedicures for a living. His attorneys have said Tourre is a low-level scapegoat.

“I am here to tell the truth and to clear my name,” he said.

As the day unfolded, there were tense moments. At one point, U.S. District Judge Katherine Forrest abruptly dismissed the jury when one of Tourre’s attorneys veered into an area deemed off-limits. Sparring between the attorneys was heated at times.

Tourre’s e-mail had previously been made public by Goldman Sachs leading up to a 2010 congressional hearing and by the Securities and Exchange Commission. Goldman was charged along with Tourre in 2010 but settled the case for $550 million without admitting or denying wrongdoing.

The SEC accuses Tourre of misleading some investors in the deal by not properly disclosing the role of the Paulson & Co. hedge fund. The government said Paulson was looking for a way to bet against the housing market, and it hired Goldman; Tourre put together a product for that purpose. The SEC alleges that he failed to disclose that Paulson played a key role in picking the stocks that went into the mortgage product. When the housing market tanked, Paulson made $1 billion off the deal.

Tourre’s defense team emphasized on Thursday that the investors were not mom-and-pop investors but sophisticated international banks and insurance companies. None were individuals, said Pamela Chepiga, his attorney.

During his testimony, Tourre told the jury of his modest start in a small town outside of Paris. His first meaningful trip to the United States took place in 1999, he said, when he did his college internship at an Ohio plant, where he assembled air conditioning units for about three months.

After graduating from college in France in 2000, he moved to California to attend Stanford, an education financed by the French government and a fellowship. His goals were to improve his English and to grow up to be a production engineer in a factory.

“I never heard of Goldman Sachs before coming to Stanford,” said Tourre, an engineer and mathematician by training.

Tourre said he stumbled upon a job at the bank when recruiters came to Stanford, and he spoke to them to hone his interviewing skills. Other potential job offers fell through. Eager to stay in the country, he joined Goldman as an analyst in New York in July 2001, he said.

Tourre climbed the ranks to become a vice president. But he said he was “one of thousands of vice presidents at Goldman.” He went on to become an executive director in the bank’s London office.

Chepiga seized on what she has previously described as Tourre’s relatively low level at the bank and noted that Tourre often reported to higher-ups about the Paulson deal, an effort to debunk the SEC’s main assertion that Tourre bore full responsibility for the deal.

Chepiga also chipped away at the SEC’s assertion that Tourre intentionally kept key investors in the dark about the mortgage deal and Paulson’s role in it. She showed the jury an e-mail listing Goldman’s top 20 clients at the time. They included some of the investors who lost money on the Abacus deal.

“It’s not good business to put your top customers in products that are designed to fail?”

With that, Tourre agreed.