NEW YORK — Mathew Martoma got off to a slow start in the hedge-fund world. A former student at Harvard Law School, he co-wrote papers on medical ethics before seeking a business degree at Stanford University and joining a little-known Boston hedge fund.

Yet in 2006, at age 32, Martoma made it to SAC Capital Advisors and gained the attention of the firm’s billionaire owner Steven A. Cohen.

Cohen, one of the most successful hedge-fund managers in the world, trusted Martoma’s recommendations enough to accumulate about $700 million in shares of Elan Corp. and Wyeth two years later, then sell them all within a week after Martoma had changed his view on the companies.

Those recommendations, which earned the young portfolio manager a $9.38 million bonus, have now landed Martoma at the center of what federal prosecutors describe as the most-lucrative insider-trading scheme they’ve ever uncovered, with profits and averted losses of $276 million.

Two weeks ago, FBI agents arrested the 38-year-old at his Boca Raton, Fla., home. The charges against him mark the first time prosecutors said Cohen had talked with a defendant about stocks in an insider-trading case, pulling the art collector deeper into one of the biggest investigations of securities fraud in history.

“Mathew Martoma was an exceptional portfolio manager who succeeded through hard work and the dogged pursuit of information in the public domain,” his lawyer Charles Stillman said in an emailed statement, adding that he expected Martoma to be fully exonerated.

Martoma grew up in Florida, living less than 10 miles from Cape Canaveral. His mother, Lizzie Thomas, was a doctor and his father, Bobby Martoma, owned a dry cleaner.

Mathew Martoma got his undergraduate degree at Duke University in 1995.

Less than two years later, he went off to Harvard. He wrote two medical-ethics papers, one of which identifies him as a member of Harvard Law’s class of 2000 and as the former deputy director of the National Human Genome Research Institute’s Office of Genome Ethics.

He left Harvard in December 1998 without attaining a degree and attended Stanford Business School, where he joined three alumni groups, including MBA Class of 2003.

In 2001, he changed his name from Ajai Mathew Mariamdani Thomas, two years after his father had changed his name to Martoma from Thomas.

In 2003, the year Martoma got married, he joined Boston-based Sirios Capital Management as a research analyst. He stayed there until 2006, when he moved to SAC’s CR Intrinsic unit, based in Stamford, Conn.

Former colleagues said Martoma had a quiet demeanor and left little impression except for an outsized trade that earned him the name “the Elan guy.”

As part of his job investing in health-care stocks, Martoma began talking to Sidney Gilman, a doctor involved in the trials of the experimental Alzheimer’s drug being developed by Elan and Wyeth, according to the complaints. Gilman eventually shared inside information on test results of an experimental Alzheimer drug with Martoma, according to prosecutors and the Securities and Exchange Commission, which has sued both men.

Based on Gilman’s inside information, Martoma built up stakes in the two companies and persuaded Cohen to do the same for the SAC account he runs, court papers say.

Cohen ignored some of his analysts who thought the Elan position was too risky, saying he had confidence in Martoma’s views because he was “closest” to the drug trial, according to the criminal complaint, which cited a March 28, 2008, instant message from Cohen.

By the end of June 2008, the hedge fund had amassed $328 million of shares of Elan and $373 million of Wyeth, the complaint says. The next month, the U.S. alleged in its complaint, Gilman tipped off Martoma that the drug-trial results would be disappointing.

SAC sold off its entire holdings, about $700 million, then bet against the two stocks, which slumped after the results were made public. The hedge fund made $76.2 million on the short sales, the government said.

“Mr. Cohen and SAC are confident that they have acted appropriately and will continue to cooperate with the government’s inquiry,” Jonathan Gasthalter, a spokesman for the $14 billion firm, said Nov. 21.

Gilman has entered into a non-prosecution agreement with the government, his lawyer, Marc Mukasey, says. He is cooperating with the SEC and the U.S. Attorneys Office, the lawyer said.

A spokesperson for the University of Michigan said Gilman has resigned. The former chairman of the university’s department of neurology and past president of the American Neurological Association also agreed to forfeit $186,781 he had earned from consulting with Elan and from his work with an expert-networking company.

Martoma’s bonus in 2008 was his last. He lost money in 2009 and 2010, and his employment was terminated that September after a SAC executive called him a “one-trick pony with Elan,” according to the complaint.

Martoma and his wife, Rosemary, a pediatrician, moved to Boca Raton, to take care of family matters, said a person familiar with him.

He spent part of his bonus on their $1.9 million, five- bedroom home, complete with six-and-a-half bathrooms, a pool, an elevator and a fake lawn. They started a foundation with $1 million. Martoma tried to start a securities business. His wife registered with the state to practice medicine.

Neighbors said the couple have three children and have kept to themselves. They are rarely seen and aren’t members of the local country club.

Martoma is free on $5 million bail cosigned by his in-laws. The charges carry a maximum 20-year prison term. The complaint does not state if Cohen knew Martoma’s advice was based on illegal insider tips. Cohen was not charged or sued.

Last month, SAC revealed it had received notice from the SEC that it is considering suing the hedge fund for fraud related to the Martoma case. The firm’s president told investors the firm would pay any potential penalties rather than investors.

SAC spokesman Gasthalter had no immediate comment.

Prosecutors said that on July 20, 2008, Martoma told an unidentified “hedge-fund owner” that he recommended selling Elan and Wyeth shares before the drug trial’s results were publicly announced. Martoma and the hedge-fund owner instructed a trader at the fund to begin selling the fund’s entire position in Elan securities on July 21, 2008, prosecutors said.

The SEC claims Martoma met Gilman through paid consultations from 2006 to 2008 arranged by an unidentified New York expert-networking firm. Gilman was chairman of the Safety Monitoring Committee overseeing the clinical trial, the SEC said. He was selected by Wyeth and Elan to present the final results at a July 29, 2008, conference.

Beginning July 17, 2008, Gilman gave Martoma “actual, detailed results” of the clinical trial, the SEC says.

The SEC claimed Martoma used Gilman’s illegal tips to trade for CR Intrinsic as well as for “hedge fund portfolios managed by an affiliated investment adviser” and controlled by an unidentified “Portfolio Manager A.” That manager was Cohen, according to a person familiar with the matter.

Neither the SEC nor the prosecution complaint says that the “hedge-fund owner” or unidentified portfolio manager knew of the source of the information.

More than 75 people have been sued by regulators or charged by prosecutors since 2008 for passing or getting inside tips about pharmaceutical, biotechnology or other health-care stocks.

At least five other current or former SAC portfolio managers or analysts have been implicated in insider trading, including Noah Freeman and Donald Longueuil and Jon Horvath.

Michael Steinberg, a portfolio manager at SAC’s Sigma Capital Management unit, has been described by prosecutors as an “unindicted co-conspirator” of Horvath, a former analyst he supervised who pleaded guilty to receiving and passing inside information.

Longueuil, who worked for SAC Capital’s CR Intrinsic unit in New York from July 2008 to July 2010, was accused of giving information to Freeman, his friend.

In 2011, ex-SAC analyst Jonathan Hollander agreed to settle SEC allegations that he traded on inside information about a pending takeover of the Albertsons chain.