The firing of U.S. Attorney Preet Bharara marks the exit of a high-profile Wall Street enforcer.

Bharara, appointed to become U.S. Attorney of the Southern District of New York by former President Barack Obama in 2009, said in a tweet on Saturday that he had been fired from his post. On Friday, the Trump administration asked remaining U.S. attorneys appointed by Obama to resign, which Bharara refused, resulting in his forced ouster. Throughout his tenure, Bharara developed a reputation for overseeing high-profile Wall Street cases.

"Part of what the office has always focused on is not just the bringing of cases but the promotion of legality," said Daniel Richman, professor of law at Columbia Law School and former federal prosecutor. "Preet across the board made an effort to advance legal norms."

"He was fair but tough," said Barry Mandel, former head of litigation at Merrill Lynch and branch chief of the SEC Enforcement Division.

Bharara made a name for himself in financial circles with his efforts on insider trading. Among his most headline-grabbing cases were the 2011 conviction of Galleon Group founder Raj Rajaratnam, for which Rajaratnam is serving an 11-year sentence, and 2013 civil and criminal charges against Steven Cohen's SAC Capital Advisors LP, which resulted in a $1.8 billion settlement.

Bharara's office successfully tried 85 successful insider trading cases before losing its first in 2014.

"I believe illegal insider trading is extremely significant and should be to everyone who cares about the protection of confidential information and the integrity of the markets," Bharara said in a speech delivered at the New York City Bar Association in 2010. "Insider trading involving a tipper and a tippee is both a theft and a fraud, and it is intolerable."

Insider trading cases out of his office slowed in recent months, due to a couple of factors--one, the deterrent effect of previous cases, and two, lack of clarity tied to matters in the Supreme Court.

Bharara's office also secured major settlements with some of the country's biggest banks, including Citibank (C) - Get Report and JPMorgan Chase (JPM) - Get Report . In 2014, it reached a $1.2 billion agreement with Toyota (TM) - Get Report over unintended acceleration by its cars.

Time Magazine ran a cover of him reading "This Man is Busting Wall Street" in 2012.

To be sure, not all of Bharara's casework was successful. A U.S. appeals court's 2014 decision that overturned two insider-trading convictions forced his office to drop some cases and rethink others. Last year, a court reversed a $1.2 billion penalty against Bank of America (BAC) - Get Report -Countrywide over violations of the Financial Institutions Reform, Recovery, and Enforcement Act (FIRREA).

Bharara was at times criticized for what some considered a failure on his part to take on the institutions and individuals responsible for the financial crisis aggressively. Observers say such a characterization is not necessarily fair.

"It was a little regrettable that the insider trading cases were taken as somehow being a substitute for or even connected to the financial collapse possibilities," Richman said. "I don't think that's an appropriate criticism given at least what it sounds like we know about the collapse."

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"Sometimes people on Wall Street are overrated. It's not that they're criminals, it's that they're not always as smart as they think they are and sometimes make bad business decisions," Mandel said. "He's taken some heat for not prosecuting executives, that's easy to do from the outside."

Bharara's office is also preparing a corruption and fraud case against former aides and associates of New York Gov. Andrew Cuomo. It has been investigating New York City Mayor Bill de Blasio's campaign fundraising activities.

"Preet was an effective and principled prosecutor, a dedicated public servant, and a great boss," said Matthew Schwartz, partner at the law firm Boies, Schiller & Flexner and a former prosecutor under Bharara, in an email. "Whoever President Trump appoints to fill that seat has a tough act to follow."

Bharara met with Trump at Trump Tower in Manhattan in November and at the time told reporters he had agreed to stay on per Trump's request. It is unclear why the administration has since changed his tune.

New York Attorney General Eric Schneiderman commended Bharara for his "integrity, tenacity and commitment to rooting out wrongdoing" in a statement. He also hit the Trump administration for its handling of the matter.

"President Trump's abrupt and unexplained decision to summarily remove over 40 U.S. Attorneys has once again caused chaos in the federal government and led to questions about whether the Justice Department's vital and non-partisan work will continue under Attorney General Sessions, as it must," he said.

A Department of Justice spokeswoman declined to comment on Bharara but confirmed he is no longer U.S. Attorney for the Southern District of New York.

The U.S. Southern District of New York could potentially deal with Trump-tied cases and matters in New York, as the office's vision of its jurisdiction has always been expansive.

While many on Wall Street aren't exactly sad to see Bharara go, they may not be breathing a sigh of relief either as his successor could very well follow in his footsteps.

"If they're breathing a sigh of relief, they're going to be disappointed, because it's important that the head of the office really has a profile that promotes deterrents," Richman said. "The office will continue to do cases of the very sort it was doing before, and I assume with the same sort of zeal."

"His departure leaves a hole at the top, but the dedicated career prosecutors in the office will make sure that ongoing investigations continue uninterrupted," Schwartz said. "Things will change under a new U.S. Attorney, as they always do, but this isn't a time for anyone to get too comfortable."

Bharara in a statement on Saturday said serving as U.S. Attorney will "forever be the greatest honor of my professional life" and emphasized the importance of "absolute independence" as a hallmark of justice. Joon Kim, Deputy U.S. Attorney, will serve as Acting U.S. Attorney until a permanent replacement is put in place.

Updated from Saturday with Bharara statement.

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