[1] In the 1980s, Icahn developed a reputation as a "corporate raider" after profiting from the hostile takeover and asset stripping of Trans World Airlines.

in philosophy in 1957 after completing a senior thesis titled "The Problem of Formulating an Adequate Explication of the Empiricist Criterion of Meaning.

[10] In 1963, he became an options manager for Tessel, Patrick & Co. and then he moved to Gruntal & Co.[15] In 1968, with $150,000 of his own money and a $400,000 investment from his uncle, M. Elliot Schnall, Icahn bought a seat on the New York Stock Exchange[10] and formed Icahn & Co., which focused on risk arbitrage and options trading.

[17] In 1978, in his first takeover attempt, he took a controlling stake in Tappan and forced the sale of the company to Electrolux, making a profit of $2.7 million, or doubling his investment.

He formed lowestfare.com to sell TWA tickets and acquired portions of Global Leisure Travel from Ramy El-Batrawi.

[18] In October 1986, Icahn launched an unsuccessful $8 billion hostile takeover for 89% of U.S. Steel; the bid was dropped in January 1987.

[21] In June 1989, in the largest share sale to date on the New York Stock Exchange, Icahn sold his stake in Texaco for $2 billion, making a profit of $700 million.

[28] In December 1998, Icahn led an investor group that acquired a 5% stake in RJR Nabisco and pressured the company's management to separate its tobacco and food units.

[37] In August 2006, Icahn bought stock in Take-Two Interactive, a video game publisher, and increased his holdings to 11.3% in 2009, becoming the company's second-largest shareholder.

[39] On February 9, 2007, Lear Corporation's board of directors accepted a $2.3 billion takeover offer from Icahn.

[48] Instead, he forced an agreement to expand Yahoo's board to eleven members, including Icahn and two others of his choice.

In March he was one of a group of lenders who purchased Tropicana Casino & Resort Atlantic City, bringing the company out of bankruptcy for $200 million.

Mentor's retaliation with a shareholder rights plan failed to deter Icahn who, in February 2011, made an unsuccessful offer to buy the company for about $1.86 billion in cash.

[75] In November 2015, Icahn hired CBRE Group to market the unfinished Fontainebleau Las Vegas to potential buyers.

[80] In August 2017, Icahn sold the unfinished Fontainebleau Resort Las Vegas for $600 million, more than four times what he paid.

[81] In January 2016, Icahn disclosed a 4.66% stake in Gannett Company[82] and also held shares in Cheniere Energy and Freeport-McMoRan, both of which declined in value.

[84] Also in October 2016, Icahn closed the Trump Taj Mahal Casino in Atlantic City, citing a $350 million loss over several years as well as failure to reach a deal with striking union workers.

[89] In February 2022 Icahn, who held 200 shares of the company, nominated two people for election to McDonald's board of directors in what may be the first step toward a proxy fight.

[91] However, in May 2022, only 1% of McDonald's' shareholders voted in favor of nominees put forward by Icahn, scoring a victory against his demands for the improvement of conditions in which pigs are raised.

In its statement, McDonald's claimed it is already moving towards a more humane approach to the issue since its pledge in 2012, adding that Icahn's demands were unreasonable.

In addition, the analysis claims that Icahn took out loans against a majority of his holdings and that these have the potential to be called should the stock price move downward.

[94] Upon becoming the presumptive Republican presidential nominee, Trump announced that he would nominate Icahn for United States Secretary of the Treasury.

[98] Icahn stepped down from this role on August 18, 2017, citing a desire not to interfere with the work of Neomi Rao as administrator of the Office of Information and Regulatory Affairs.

[99][100][101][102][11] In February 2018, Icahn avoided a $6 million loss by selling some of his holdings in a steel-price sensitive stock just days before the Trump administration announced a 25% tariff on steel imports.

[104] The Sugar Land, Texas oil refinery benefited when President Trump made an exception to his regulation freeze to expand the tax advantage of master limited partnerships.

In October 1993, Liba filed for divorce and sued to invalidate the prenuptial agreement, claiming she signed it under duress due to the pregnancy.

[114] Icahn is an activist investor, and has worked with the Humane Society of the United States in pushing McDonald's to achieve its pledge to end the sourcing of pork produced with gestation crates.

In 2004, Icahn shut down Foxfield, selling all his mares and weanlings without reserve at the Keeneland Sales November breeding stock auction.