Who Is Bill Ackman, Trump Supporter Slamming Tariff Policy As "Bad Math"

Billionaire investor and Donald Trump supporter Bill Ackman has trained his guns on the US President's latest tariff policy, calling it a dangerous misstep capable of severely damaging America's economic reputation.

In a rare public rebuke, Ackman said Trump's tariff formula was based on "bad math," making the levies appear four times higher than they actually were. "The global economy is being taken down because of bad math," he wrote on X.

The formula used by the administration to calculate tariffs made other nations' tariffs appear four times larger than they actually are.

President @realDonaldTrump is not an economist and therefore relies on his advisors to do these calculations so he can determine policy.… https://t.co/haPHKrxWOR

— Bill Ackman (@BillAckman) April 7, 2025

Ackman warned that the disproportionate tariffs are undermining the world's confidence in the US as a reliable trading partner. "The President is losing the confidence of business leaders around the globe," he said. "This is not what we voted for."

Who is Bill Ackman?

William Albert Ackman was born on May 11, 1966, in Chappaqua, New York. He graduated magna cum laude from Harvard College in 1988 with a degree in social studies.

While an undergraduate at Harvard, Bill Ackman sold ads for 'Let's Go' travel guides from his dorm room. During his time at Harvard Business School, he co-captained the crew team, whose oars were decorated with dollar signs. After the team was booed, he wrote in the school newspaper, "Let's face up to what Harvard Business School represents... We spend 90 per cent of our studies at HBS pursuing the maximisation of the dollar."

In 1992, he earned an MBA from Harvard Business School. 

The same year, he co-founded Gotham Partners, a small investment firm, with David Berkowitz. By 1998, Gotham Partners had grown to manage $500 million in assets. In 2002, the firm faced legal disputes and was eventually shut down.

In between, he married Karen Ann Herskovitz, a landscape architect, from 1994 to 2016. They had three daughters together.

Bill Ackman founded Pershing Square Capital Management in 2004, a hedge fund that currently manages $15 billion in assets. Pershing Square's investment portfolio is highly concentrated, with major holdings in companies like Chipotle, Hilton, and Alphabet (Google's parent).

In 2010, he took a major stake in JC Penney and joined the board, but exited in 2013 after internal clashes.

By 2011, The New York Times referred to him as the finance world's "smart-alecky boy wonder."

In 2012, Ackman publicly accused Herbalife of being a pyramid scheme and shorted $1 billion of its stock. In 2016, he testified before the US Senate about Valeant Pharmaceuticals' pricing practices.

He endorsed Donald Trump in the 2024 presidential election after decades of backing Democratic candidates, saying the current Democratic Party no longer reflected his values.

Bill Ackman met his second wife, Neri Oxman, in 2017. He said marrying Oxman, who is Israeli, made him feel deeply connected to the October 7 Hamas attack. 

When his wife faced plagiarism accusations in January 2024, Bill Ackman believed this attack was aimed at him, through his wife. He reacted strongly and began attacking Business Insider online.

He promised to check every MIT professor's work for plagiarism and even said he would investigate Business Insider reporters. He spent a weekend calling the outlet's leadership to demand the story be taken down.

In 2024, Bill Ackman's vocal opposition to a pro-Palestinian student letter at Harvard after the October 7 Hamas attack expanded into a full-fledged campaign against diversity, equity, and inclusion (DEI) initiatives and elite academia.

He was a key figure in pressuring Harvard President Claudine Gay to resign amid growing scrutiny of her handling of campus tensions and allegations of plagiarism.

His net worth is $8.8 billion, as per Forbes.