A 50-Pound Book Holds the Keys to Citadel Securities’ Future

One of the driving forces behind Citadel Securities, the Wall Street titan that trades $652 billion a day across high-speed networks, is a physical book.

It runs hundreds of pages, bound in a binder using special paper so thick it takes a full day to print. Resembling a corporate grimoire, the tome is roughly the width of an iMac and estimated to weigh 50 pounds. Once complete, the annual “goal book,” as it’s called internally, is hand-delivered to Chief Executive Officer Zhao Peng, a former math Olympiad prodigy who likes to fill its pages with scribbles, notes and challenges ...