Preet Bharara is known for his fierce pursuit of insider trading and corruption cases. Now, he's out.

On Friday, Bharara was one of 46 U.S. attorneys asked to resign by President Trump. That was a standard move for a new president. But Trump, during his transition, had asked Bharara to stay on. After Bharara refused to resign, he was fired by Trump on Saturday.

Bharara, 48 and born in Punjab, India, was appointed as U.S. attorney for the Southern District of New York by former President Obama. His parents immigrated to the United States in 1970, and Bharara got degrees from Harvard and Columbia University School of Law. He started work as Democratic Senator Charles Schumer's chief counsel in 2006.

Then, during the depths of the financial crisis in 2009, Bharara got the coveted prosecutor's job in New York. Because it oversees federal crime in Manhattan, the U.S. attorney's office in the Southern District has a rich history prosecuting cases involving Wall Street and banks.

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And Bharara prosecuted scores of financiers, some of whom are now behind bars.

One of his most high-profile cases was that of Raj Rajaratnam, a former hedge fund manager, who was sentenced to 11 years in prison and fined $93 million in 2011 on insider trading charges brought by Bharara.

The man who leaked information to Rajartnam, former Goldman Sachs board member Rajat Gupta, received a two-year prison sentence in 2012.

"He's had a very, very significant impact," said John Coffee, the director of the Center on Corporate Governance at Columbia Law School. "There were other [U.S. attorneys ] that prosecuted insider trading, but none as rigorously and systematically."

Bharara's most prized target was hedge-fund billionaire Steve Cohen. He never made a criminal case against Cohen but he went after several employees of Cohen's SAC Capital, and the company was fined $1.8 billion in 2013.

More recently, Bharara prosecuted two executives from Valeant Pharmaceuticals who were arrested in November last year and charged with concocting a massive fraud scheme.

The Civil Frauds Unit that Bharara created landed nearly $500 million in settlements. That includes multi-million dollar deals with CitiMortgage and Deutsche Bank for engaging in the type of reckless lending practices that led to the financial crisis.

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But Bharara was criticized by some who thought he didn't do enough to push criminal charges against financial fraudsters. A column in the Guardian was headlined: "Why is Preet Bharara, the 'scourge of Wall Street', taking a friendly tone towards mortgage bankers?"

Bharara defended his office against those claims. He cited a lack of evidence as a reason for his restraint. At a National Press Club event in 2014, Bharara said the lack of criminal cases "has not been as a result of a lack of effort," the Atlantic reported.

He'll also leave behind a legacy of aggressively prosecuting political corruption. Bharara extensively investigated officials in Albany, the New York state capital, and secured "convictions against multiple elected officials and other corrupt public servants," according to his office.

Bharara's exploits taking on hedge funds inspired the Showtime series "Billions," in which Paul Giamatti plays a cutthroat federal prosecutor.

Brian Koppelman, the co-creator of Billions, said on Twitter on Saturday that he's not surprised by how Bharara's departure played out.

A few times last season people were like: are you sure US Attorney's Office stuff is this political. We were like: ummmmm, yas. — Brian Koppelman (@briankoppelman) March 11, 2017