Only months ago, Ackman was celebrating Trump’s administration as "the most pro-growth, pro-business, pro-American” he’d seen in his adult life.

Only months ago, Ackman was celebrating Trump’s administration as "the most pro-growth, pro-business, pro-American” he’d seen in his adult life.

Photographer: Jeenah Moon/Bloomberg
The Big Take

‘My Bad’: Bill Ackman Lays Bare Wall Street’s Big Fail on Trump

As trillions vanish from markets, the smart money gets a hard lesson about the president it was betting on.

“My bad.”

It was nearly 9 p.m. and Bill Ackman, public face of the billionaire class that embraced Donald Trump, was tweeting his way into the eye of the financial storm.