Hedge fund maestro Bill Ackman took a $200 million bath in his failed attempts to breathe fresh life into floundering bookseller Borders back in 2011, according to an upcoming book.

“Borders was a big mistake on the buy,” Ackman, who runs $11 billion Pershing Square Capital, explains in the hedge-fund tome “The Alpha Masters: Unlocking the Genius of the World’s Top Hedge Funds.”

Penned by CNBC producer and Wall Street insider Maneet Ahuja, the book is set to be widely released May 29.

The narrative offers broad insights into some of the hedge fund universe’s most tight-lipped managers.

A handful of the managers profiled in the book — including the often-paranoid genius Ray Dalio at Bridgewater Associates and Appaloosa Management’s star money manager, David Tepper — typically go out of their way to fly beneath the radar, in favor of ringing up returns at their closely held investment firms, so their appearance in these pages is a coup.