Hey there. Preston here, covering for Orianna while she’s moderating at Web Summit in Doha.

The most open secret in business may also be one of the simplest: Successful people read. A lot.

Marc Andreessen is a case in point. For the billionaire behind venture capital firm Andreessen Horowitz, books aren’t a leisure activity—they’re a tool for understanding how the world works. And that understanding shapes how he invests, builds, and thinks.

The 54-year-old spends two to three hours a day immersed in audiobooks (he switched over from physical books after he discovered AirPods). He typically rotates between history, biography, and material in new subject areas like artificial intelligence. Add it up, and he logs nearly a full 24-hour day of learning every week.

“If nothing else is going on. I’m always listening to something,” Andreessen said.

He’s far from an outlier. Countless business leaders—the likes of Bill Gates, Warren Buffett, and Mark Cuban—have long advocated that reading is a competitive advantage—a way to widen perspective while others stay stuck in the day-to-day.

And a new report from JPMorgan has cemented the idea as more than anecdotal but rather a tried-and-true practice: Reading is the most commonly cited behavior tied to long-term success, according to the survey of more than 100 billionaires with a combined net worth exceeding $500 billion.

Reading as a core habit is something that Kurt Strovink, one of McKinsey’s top “CEO whisperers,” sees among many high-performing leaders. But, he added, the value of reading isn’t about just keeping up with the headlines—it’s about sharpening judgement.

“In a role defined by constant pressure and limited time, choosing to read is a deliberate act. It is one way to step up unto the balcony and off the dance floor,” Strovink wrote on LinkedIn.

“It is a management practice that pays dividends—for clarity, for perspective, and for the quality of decisions leaders make on behalf of the institutions and people they serve.”

In other words, the edge isn’t a single book. It’s the habit itself. The consistent exposure to new ideas, different eras, and unfamiliar fields builds the mental range leaders draw on when the stakes are high and answers aren’t clear.

What’s the best book you’ve read (or listened to) lately? Reply to this newsletter and let me know.

—Preston Fore
Success Reporter, Fortune

Got a career tip or dilemma? Get in touch: preston.fore@fortune.com. You can also find Preston on Linkedin: @forepreston.