Walmart's US CEO Bill Simon, once on track to head the entire company, is out amid reports of sluggish sales and slow growth. He had been with Walmart since 2010. Here are some other shocking CEO departures and downfalls, some for far more nefarious reasons than others.
J.P. Bolduc (W.R. Grace) -- Bolduc, the former CEO of chemical company W.R. Grace, left abruptly in 1995 amid allegations of sexual harassment. Bolduc denied the allegations, but stated in a press release he was quitting because of "differences in style and philosophy."
Joseph Nacchio (Qwest) -- In the wake of a multibillion-dollar accounting scandal that nearly destroyed the Denver-based telecommunications company, Nacchio was convicted in April 2007 on 19 counts of insider trading. He had resigned five years earlier amid the insider trading rumors.
Olli-Pekka Kallasvuo (Nokia) -- In September 2010, Nokia announced it was replacing Kallasvuo as CEO after the company's dismal performance against Apple's iPhone to placate angry investors.
Jeff Papows (Lotus Development Corp) -- Papows resigned in 2000 after a year embroiled in controversy. A former executive of his company filed a sexual discrimination complaint and the Wall Street Journal reported that he may have liedabout his personal history to boost Lotus' sales and its image.
Richard Fuld (Lehman Brothers) -- He became the target of public anger over Wall Street excess after the bank's failure set off the financial meltdown, so much so that an employee reportedly punched him in the company gym. In Lehman's waning days, Fuld tried furiously to find a buyer or a government lifeline, but it was too late.
Mark Hurd (Hewlett Packard) -- He resigned in 2010 amid sexual harassment allegations. While an investigation found no sexual harassment was involved, it did reveal Hurd had a relationship with a contractor who received payments that were deemed "inappropriate."
Chris Albrecht (HBO) -- He abruptly ended a long career at HBO in 2007 after being charged with assaulting his girlfriend. The company told him to resign or he'd be fired.
Ed Whitacre (GM) -- The news in September 2010 that Whitacre was being replacedcame as a surprise, as it happened just days before GM's initial public offering. It also came less than a year after he became the company's permanent CEO.
Richard Syron (far left) and Daniel Mudd (second from left) (Freddie Mac and Fannie Mae) -- As CEOs of the government's mortgage giants, Syron and Mudd were sued and became the highest-profile individuals to be charged in the 2008 financial crisis. They were accused of understating the level of high-risk subprime mortgages just before the housing bubble burst. Both were fired in 2008. Also pictured are former Freddie Mac CEO Leland Brendsel (second from right) and former Fannie Mae CEO Franklin Raines (right).
Kenneth Lay (pictured) and Jeffrey Skilling (Enron) -- Both men served at times as CEO of energy giant Enron, which imploded in the early 2000s after it became the largest U.S. company to file for bankruptcy. Skilling resigned as CEO shortly before the breaking point and cashed out $60 million in stock. Both men were later tried together and convicted in May 2006 on fraud and conspiracy charges.
Robert Pace Andrews (Andrews Technologies) -- The ex-husband of George W. Bush's brother's wife, Andrews was fired after pleading guilty to cocaine charges in the 2008 overdose death of a stripper at his townhouse.
Vikram Pandit (Citigroup) -- He was forced out of Citigroup in October 2012 by new chairman Michael O'Neill despite strong earnings. According to The New York Times, O'Neill told Pandit he had readied three news releases -- one that said he had resigned immediately, one that said he would resign at the year's end and a third saying he had been fired without cause. O'Neill reportedly told Pandit the board had lost confidence in him, and the choice was his.
Bernard Madoff (Bernard Madoff Investment Securities) -- In one of history's biggest swindles, Madoff's decades-long, $65 billion Ponzi scheme came to a screeching halt with his December 2008 arrest and earned him 150 years in prison. He had been widely regarded as a pillar of the investment community, and his son later committed suicide over the charges.
Tony Hayward (BP) -- He became one of the most reviled men in America following the Gulf oil spill in 2010. Hayward's statements dubbing the spill "relatively tiny" and later saying "I want my life back" only further tarnished the company's image, and he was ousted as CEO that summer.
Lord Browne (BP) -- Before Tony Hayward, there was Lord Browne. The former BP CEO resigned in 2007 after embarrassing details of his gay sex life were brought up in a court case and published in the media. The juicy details also cost him at least 3.5 million pounds from his retirement package.
Harry Stonecipher (Boeing) -- The former CEO was asked in 2003 to come back to Boeing to boost the firm's reputation, but only further sullied it after it came out that he had an affair with a female employee. Stonecipher resigned in 2005.
Richard Schulze (Best Buy) -- Pictured with Microsoft President Steve Ballmer (L), the Best Buy founder (R) stepped down as chairman in May 2012 after an investigation found that he knew the CEO was having a relationship with a female employee and did not alert the audit committee. Later that year, he made a bid to buy the company but that move has since fizzled out.
John Rigas (Adelphia) -- The Rigas family founded the cable provider, but John Rigas was forced to retire as CEO in 2002 after being indicted for securities, bank and wire fraud. Adelphia filed for bankruptcy after admitting that the former CEO and his two sons had failed to record $3.1 billion in loans.
Jeff Zucker (NBC) -- First hired by NBC in 1986 as a researcher, Zucker was paid to quit as CEO of NBC Universal in 2010 amid reports of differences with Comcast CEO Steve Burke. Comcast announced plans that year to acquire 51 percent of the broadcasting company. During his tenure as CEO of NBC Universal, Zucker saw the network go from No. 1 to the lowest rated of the four major networks.
Martha Stewart (Martha Stewart Living) -- Homemakers nationwide were shocked when Stewart resigned in 2003 as CEO of Martha Stewart Living over insider trading charges. In 2004, she was found guilty of obstruction of justice, making false statements and perjury, and served prison time.
Andrew Mason (Groupon) -- He was fired in 2013 from the company he co-founded following disastrous financial losses. But Mason didn't go out without a fight, raising eyebrows with his email to employees that began: "I've decided that I'd like to spend more time with my family. Just kidding -- I was fired today."
Gregg Steinhafel (Target) -- In a surprise move, he was ousted in May 2014 in the wake of last year's massive data breach involving up to 110 million customers. He had been with the company for 35 years.
Dov Charney (American Apparel) -- Charney was ousted by board members in June 2014 for an unspecified reason, although one board member said the decision grew out of an ongoing investigation into misconduct. Charney faces a series of sexual harassment suits filed by employees in recent years. He founded the company in 1998.