(CNN) -- Here's a look at what you need to know about Enron.
Before its collapse, Enron marketed electricity and natural gas, delivered energy and other physical commodities, and provided financial and risk management services to customers around the world.
Facts: Most of the top executives were tried for fraud after it is revealed in November 2001 that Enron's earnings had been overstated by several hundred million dollars.
Enron was once ranked the sixth largest energy company in the world.
Enron shares were worth $90.75 at their peak in August 2000 and dropped to $0.67 in January 2002.
Top Enron executives sold their company stock prior to the company's downfall.
Lower-level employees were prevented from selling their stock due to 401k restrictions and many subsequently lost their life savings.
Enron paid the top 140 executives $680 million in 2001. Kenneth Lay received $67.4 million and Jeffrey Skilling received $41.8 million.
Timeline: July 1985 - Enron is formed by the merger of Houston Natural Gas and Omaha-based InterNorth.
2000 - Enron reaches No. 7 on the Fortune 500 list.
August 14, 2001 - Jeffrey Skilling resigns as CEO, and Kenneth Lay becomes CEO again (He had been CEO from 1985-2000).
August 15, 2001 - Sherron Watkins sends a memo to Kenneth Lay about accounting issues.
October 16, 2001 - Enron announces a third quarter loss of $618 million.
October 31, 2001 - The SEC opens a formal investigation into Enron's transactions.
November 9, 2001 - Enron and Dynegy announce the $7.8 billion merger agreement. It would form Dynegy Corp, in which Dynegy would own 64% and Enron 36%.
November 28, 2001 - Dynegy announces it has terminated merger talks with Enron.
December 2, 2001 - Enron files for Chapter 11 protection, becoming the largest bankruptcy in U.S. history at that time and leaves thousands of workers with worthless stock in their pensions.
January 9, 2002 - U.S. Department of Justice opens a criminal investigation into Enron's collapse.
January 11, 2002 - The SEC widens its investigation to include Enron's chief auditor, Arthur Andersen, due to reports of document shredding.
January 15, 2002 - The NYSE suspends trading of Enron shares.
January 17, 2002 - Enron ends its partnership with Arthur Andersen.
January 23, 2002 - Kenneth Lay resigns as chairman of the board and CEO.
January 25, 2002 - Former Enron vice chairman J. Clifford Baxter commits suicide in Sugarland, Texas.
January 30, 2002 - Enron appoints Stephen Cooper as its interim CEO.
February 4, 2002 - Kenneth Lay resigns from Enron's board of directors.
February 7, 2002 - Andrew Fastow, Michael Kopper, Richard Buy and Richard Causey all invoke their Fifth Amendment rights before the House Energy and Commerce Committee.
February 12, 2002 - Kenneth Lay invokes his Fifth Amendment right before the Senate Commerce Committee.
February 14, 2002 - Whistleblower Sherron Watkins testifies before the House of Representatives.
February 26, 2002 - Jeffrey Skilling, Sherron Watkins and Jeffrey McMahon testify before the U.S. Senate Commerce Committee.
March 14, 2002 - U.S. Justice Department indicts accounting firm Arthur Andersen for obstruction of justice in the Enron case.
April 2002 - Enron rises to No. 5 on the Fortune 500 list despite its bankruptcy filing. Fortune bases its rankings only on the first nine months of revenue in 2001, which total $138.7 billion.
June 15, 2002 - Arthur Andersen found guilty of obstructing justice.
August 21, 2002 - Former Enron executive Michael Kopper pleads guilty to conspiracy to commit wire fraud and money laundering conspiracy.
October 2, 2002 - Andrew Fastow is charged with securities fraud, wire fraud, mail fraud, money laundering and conspiracy.
May 1, 2003 - Andrew Fastow, his wife, and seven others are charged in a superseding indictment for actions relating to the firm's financial scandals.
January 8, 2004 - Judge David Hittner says he will accept Lea Fastow's plea deal in exchange for a guilty plea that could reduce her prison time.
January 14, 2004 - Andrew and Lea Fastow each plead guilty, as part of a plea agreement.
January 22, 2004 - Richard Causey pleads not guilty to five counts of securities fraud and one count of conspiracy to commit securities fraud.
February 19, 2004 - Former Enron CEO Jeffrey Skilling is indicted on fraud and conspiracy charges and pleads not guilty.
May 19, 2004 - The former Enron vice president responsible for investor relations, Paula Rieker, pleads guilty to insider trading.
July 7, 2004 - Lay is indicted on 11 counts - one count of conspiracy to commit security and wire fraud, two counts of wire fraud for misleading statements at employee meetings, four counts of securities fraud for false statements in presentations to securities analysts, one count of bank fraud and three counts of making false statements to banks.
November 3, 2004 - The first criminal trial ends with the acquittal of former accountant Sheila Kahanek.
November 17, 2004 - Enron comes out of bankruptcy after selling its interest in three natural gas pipelines to CCE Holdings for $2 billion.
May 31, 2005 - The U.S. Supreme Court overturns Arthur Andersen's obstruction of justice conviction.
December 28, 2005 - Richard Causey pleads guilty to securities fraud for his role in the Enron scandal. He will serve only seven years in exchange for cooperating with prosecutors seeking convictions of his former bosses, Lay and Skilling.
March 28, 2006 - The judge dismisses three counts against Skilling (two charges of securities fraud and one charge of lying to auditors) and one count of securities fraud against Lay.
May 25, 2006 - The jury in the Enron case finds former CEO Jeffrey Skilling and founder Kenneth Lay guilty of conspiracy and fraud. Lay is convicted of all six counts against him and Skilling is found guilty on 19 counts of conspiracy, fraud, false statements and insider trading. Skilling is found not guilty on nine counts of insider trading. Judge Simeon T. Lake announces four guilty verdicts in the separate bench trial of Lay on separate counts of conspiracy and fraud.
July 5, 2006 - Ken Lay dies in Aspen, Colorado from a heart attack brought on by severe coronary artery disease.
September 26, 2006 - Andrew Fastow is sentenced to six years in prison, four years less than his plea agreement stipulated in January 2004.
October 17, 2006 - Judge Lake erases Lay's fraud and conspiracy convictions. This is a long-standing legal practice of the U.S. federal courts if the defendant dies before he/she has a chance for an appeal to be heard.
October 23, 2006 - Jeffrey Skilling is sentenced to 24 years and four months in prison.
November 7, 2006 - Fastow reports to the Oakdale, Louisiana federal detention center to begin serving his six-year sentence.
November 15, 2006 - Former COO Richard Causey is sentenced to five years and six months in prison for one count of securities fraud.
November 16, 2006 - Jeffrey Skilling appeals his convictions to the 5th Circuit Court of Appeals.
December 13, 2006 - Skilling reports to prison in Waseca, Minnesota, after a judge refuses to allow him to remain free pending appeal.
January 3, 2007 - Richard Causey reports to the Bastrop Federal Correctional Institution to begin serving his five and a half year sentence.
January 6, 2009 - The U.S. Court of Appeals affirms Skilling's conviction but sends his case back for resentencing.
June 24, 2010 - The U.S. Supreme Court rules that Skilling was incorrectly prosecuted under a law concerning "honest-services fraud." The court then nullifies Skilling's conviction on that charge.
April 6, 2011 - The Fifth U.S. Circuit Court of Appeals confirms Skilling's criminal conviction.
May 16, 2011 - Andrew Fastow is transferred from a federal prison in Louisiana to a halfway house in Houston. He is later allowed to move to his home to complete his sentence.
May 17, 2011 - Richard Causey begins serving the rest of his five and a half year sentence in home confinement.
December 17, 2011 - Fastow's home confinement ends and he begins two years of probation.
April 16, 2012 - The U.S. Supreme Court turns aside Jeffrey Skilling's second appeal. A few weeks later, Skilling's attorney files a motion requesting a new trial in Houston federal court citing newly discovered evidence.
June 21, 2013 - A federal judge reduces Skilling's sentence by more than 10 years. As part of the resentencing deal brokered between prosecutors and the defense, Skilling agrees to stop challenging his conviction and forfeit roughly $42 million that will be distributed among the victims of the Enron fraud.